2024算法基础公选课练习六(综合3)
一、前言
最后三题有点难度,其他都还是比较基础的,前面题我直接放代码了
二、题目总览
三、具体题目
3.1 问题 A: 一锐家的电池
我的代码
#include <bits/stdc++.h>
using i64 = long long;
using pii = std::pair<int,int>;
constexpr int N = 1e5+5,M = 1e6+5,INF = 0x3f3f3f3f;
void solve(){
int n;std::cin >> n;
std::vector<std::string> v(N);
int ans = 1;
for(int i = 0;i<n;++i){
std::cin >> v[i];
}
for(int i = 1;i<n;++i){
if(v[i]!=v[i-1]){
++ans;
}
}
std::cout << ans << '\n';
}
int main(){
std::cin.tie(nullptr)->sync_with_stdio(false);
int t = 1;
// std::cin >> t;
for(int ti = 0;ti<t;++ti) {
solve();
}
return 0;
}
3.2 问题 B: 新年礼物
我的代码
#include <bits/stdc++.h>
using i64 = long long;
using pii = std::pair<int,int>;
constexpr int N = 1e5+5,M = 1e6+5,INF = 0x3f3f3f3f;
void solve(){
int n,m;std::cin >> n >> m;
std::vector<int> v(105,0);
for(int i = 1;i<=m;++i) std::cin >> v[i];
std::sort(v.begin()+1,v.begin()+1+m);
int ans = INF;
for(int i = 1;i<=m-n+1;++i){
int min = v[i],max = v[i+n-1];
ans = std::min(ans,max-min);
}
std::cout << ans << '\n';
}
int main(){
std::cin.tie(nullptr)->sync_with_stdio(false);
int t = 1;
// std::cin >> t;
for(int ti = 0;ti<t;++ti) {
solve();
}
return 0;
}
3.3 问题 C: 虎哥坐公交
我的代码
#include <bits/stdc++.h>
using i64 = long long;
using pii = std::pair<int,int>;
constexpr int N = 1e5+5,M = 1e6+5,INF = 0x3f3f3f3f;
int n,t;
std::vector<pii> v(N);
void solve(){
std::cin >> n >> t;
for(int i = 1;i<=n;++i){
std::cin >> v[i].first >> v[i].second;
}
std::vector<int> ans;
for(int i = 1;i<=n;++i){
if(t<=v[i].first){
ans.emplace_back(v[i].first);
}else{
int tmp = ((t-v[i].first)+v[i].second-1)/v[i].second;
tmp = v[i].first+tmp*v[i].second;
ans.emplace_back(tmp);
}
}
int min = INF,res = -1;
for(int i = 0;i<ans.size();++i){
if(ans[i]<min){
min = ans[i],res = i+1;
}
}
std::cout << res << '\n';
}
int main(){
std::cin.tie(nullptr)->sync_with_stdio(false);
int t = 1;
// std::cin >> t;
for(int ti = 0;ti<t;++ti) {
solve();
}
return 0;
}
3.4 问题 D: 跳格子
我的代码
#include <bits/stdc++.h>
using i64 = long long;
using pii = std::pair<int,int>;
constexpr int N = 1e5+5,M = 1e6+5,INF = 0x3f3f3f3f;
int __lcm(int a,int b){
return a*b/std::__gcd(a,b);
}
void solve(){
int x,y,a,b;std::cin >> x >> y >> a >> b;
int lcm = __lcm(x,y);
int st = a/lcm;
int ed = (b+lcm-1)/lcm;
int ans = ed-st+1;
if(st*lcm!=a) --ans;
if(ed*lcm!=b) --ans;
ans = std::max(0,ans);
std::cout << ans << '\n';
}
int main(){
std::cin.tie(nullptr)->sync_with_stdio(false);
int t = 1;
// std::cin >> t;
for(int ti = 0;ti<t;++ti) {
solve();
}
return 0;
}
3.5 问题 E: 城市公园里的长凳
我的代码
实际上long long就可以存的下了,不过我用的高精度实现的大整数类来写也可以
#include <bits/stdc++.h>
using i64 = long long;
using pii = std::pair<int,int>;
constexpr int N = 1e5+5,M = 1e6+5,INF = 0x3f3f3f3f;
//ctto
typedef long long ll;
typedef long double ld;
typedef std::complex<ld> pt;
const int MOD = 1e9 + 7;
const ld PI = acos(-1.L);
template<class T> struct cplx {
T x, y;
cplx() {
x = 0.0;
y = 0.0;
}
cplx(T nx, T ny = 0) {
x = nx;
y = ny;
}
cplx operator+(const cplx &c) const {
return {x + c.x, y + c.y};
}
cplx operator-(const cplx &c) const {
return {x - c.x, y - c.y};
}
cplx operator*(const cplx &c) const {
return {x*c.x - y * c.y, x*c.y + y * c.x};
}
cplx& operator*=(const cplx &c) {
return *this = {x*c.x - y * c.y, x*c.y + y * c.x};
}
inline T real() const {
return x;
}
inline T imag() const {
return y;
}
// Only supports right scalar multiplication like p*c
template<class U> cplx operator*(const U &c) const {
return {x * c, y * c};
}
template<class U> cplx operator/(const U &c) const {
return {x / c, y / c};
}
template<class U> void operator/=(const U &c) {
x /= c;
y /= c;
}
};
#define polar(r,a) (cplx<ld>){r*cos(a),r*sin(a)}
const int DIG = 9, FDIG = 4;
const int BASE = 1e9, FBASE = 1e4;
typedef cplx<ld> Cplx;
// use mulmod when taking mod by int v and v>2e9
// you can use mod by bigint in that case too
struct BigInt {
int sgn;
std::vector<int> a;
BigInt() : sgn(1) {}
BigInt(ll v) {
*this = v;
}
BigInt& operator = (ll v) {
sgn = 1;
if (v < 0) sgn = -1, v = -v;
a.clear();
for (; v > 0; v /= BASE) a.push_back(v % BASE);
return *this;
}
BigInt(const BigInt& other) {
sgn = other.sgn;
a = other.a;
}
friend void swap(BigInt& a, BigInt& b) {
std::swap(a.sgn, b.sgn);
std::swap(a.a, b.a);
}
BigInt& operator = (BigInt other) {
swap(*this, other);
return *this;
}
BigInt(BigInt&& other) : BigInt() {
swap(*this, other);
}
BigInt(const std::string& s) {
read(s);
}
void read(const std::string& s) {
sgn = 1;
a.clear();
int k = 0;
for (; k < s.size() && (s[k] == '-' || s[k] == '+'); k++)
if (s[k] == '-') sgn = -sgn;
for (int i = s.size() - 1; i >= k; i -= DIG) {
int x = 0;
for (int j = std::max(k, i - DIG + 1); j <= i; j++) x = x * 10 + s[j] - '0';
a.push_back(x);
}
trim();
}
friend std::istream& operator>>(std::istream &in, BigInt &v) {
std::string s;
in >> s;
v.read(s);
return in;
}
friend std::ostream& operator<<(std::ostream &out, const BigInt &v) {
if (v.sgn == -1 && !v.zero()) out << '-';
out << (v.a.empty() ? 0 : v.a.back());
for (int i = (int) v.a.size() - 2; i >= 0; --i)
out << std::setw(DIG) << std::setfill('0') << v.a[i];
return out;
}
bool operator<(const BigInt &v) const {
if (sgn != v.sgn) return sgn < v.sgn;
if (a.size() != v.a.size()) return a.size() * sgn < v.a.size() * v.sgn;
for (int i = (int)a.size() - 1; i >= 0; i--)
if (a[i] != v.a[i]) return a[i] * sgn < v.a[i] * sgn;
return 0;
}
bool operator>(const BigInt &v) const {
return v < *this;
}
bool operator<=(const BigInt &v) const {
return !(v < *this);
}
bool operator>=(const BigInt &v) const {
return !(*this < v);
}
bool operator==(const BigInt &v) const {
return !(*this < v) && !(v < *this);
}
bool operator!=(const BigInt &v) const {
return *this < v || v < *this;
}
friend int __cmp(const BigInt& x, const BigInt& y) {
if (x.a.size() != y.a.size()) return x.a.size() < y.a.size() ? -1 : 1;
for (int i = (int) x.a.size() - 1; i >= 0; --i) if (x.a[i] != y.a[i])
return x.a[i] < y.a[i] ? -1 : 1;
return 0;
}
BigInt operator-() const {
BigInt res = *this;
if (zero()) return res;
res.sgn = -sgn;
return res;
}
void __add(const BigInt& v) {
if (a.size() < v.a.size()) a.resize(v.a.size(), 0);
for (int i = 0, carry = 0; i < std::max(a.size(), v.a.size()) || carry; ++i) {
if (i == a.size()) a.push_back(0);
a[i] += carry + (i < (int) v.a.size() ? v.a[i] : 0);
carry = a[i] >= BASE;
if (carry) a[i] -= BASE;
}
}
void __sub(const BigInt& v) {
for (int i = 0, carry = 0; i < (int) v.a.size() || carry; ++i) {
a[i] -= carry + (i < (int) v.a.size() ? v.a[i] : 0);
carry = a[i] < 0;
if (carry) a[i] += BASE;
}
this->trim();
}
BigInt operator+=(const BigInt& v) {
if (sgn == v.sgn) __add(v);
else if (__cmp(*this, v) >= 0) __sub(v);
else {
BigInt vv = v;
swap(*this, vv);
__sub(vv);
}
return *this;
}
BigInt operator-=(const BigInt& v) {
if (sgn == v.sgn) {
if (__cmp(*this, v) >= 0) __sub(v);
else {
BigInt vv = v;
swap(*this, vv);
__sub(vv);
sgn = -sgn;
}
} else __add(v);
return *this;
}
template< typename L, typename R >
typename std::enable_if <
std::is_convertible<L, BigInt>::value &&
std::is_convertible<R, BigInt>::value &&
std::is_lvalue_reference < R&& >::value,
BigInt >::type friend operator + (L&& l, R&& r) {
BigInt result(std::forward<L>(l));
result += r;
return result;
}
template< typename L, typename R >
typename std::enable_if <
std::is_convertible<L, BigInt>::value &&
std::is_convertible<R, BigInt>::value &&
std::is_rvalue_reference < R&& >::value,
BigInt >::type friend operator + (L&& l, R&& r) {
BigInt result(move(r));
result += l;
return result;
}
template< typename L, typename R >
typename std::enable_if <
std::is_convertible<L, BigInt>::value &&
std::is_convertible<R, BigInt>::value,
BigInt >::type friend operator - (L&& l, R&& r) {
BigInt result(std::forward<L>(l));
result -= r;
return result;
}
friend std::pair<BigInt, BigInt> divmod(const BigInt& a1, const BigInt& b1) {
ll norm = BASE / (b1.a.back() + 1);
BigInt a = a1.abs() * norm, b = b1.abs() * norm, q = 0, r = 0;
q.a.resize(a.a.size());
for (int i = a.a.size() - 1; i >= 0; i--) {
r *= BASE;
r += a.a[i];
ll s1 = r.a.size() <= b.a.size() ? 0 : r.a[b.a.size()];
ll s2 = r.a.size() <= b.a.size() - 1 ? 0 : r.a[b.a.size() - 1];
ll d = ((ll) BASE * s1 + s2) / b.a.back();
r -= b * d;
while (r < 0) r += b, --d;
q.a[i] = d;
}
q.sgn = a1.sgn * b1.sgn;
r.sgn = a1.sgn;
q.trim();
r.trim();
auto res = std::make_pair(q, r / norm);
if (res.second < 0) res.second += b1;
return res;
}
BigInt operator/(const BigInt &v) const {
return divmod(*this, v).first;
}
BigInt operator%(const BigInt &v) const {
return divmod(*this, v).second;
}
void operator/=(int v) {
if (llabs(v) >= BASE) {
*this /= BigInt(v);
return;
}
if (v < 0) sgn = -sgn, v = -v;
for (int i = (int) a.size() - 1, rem = 0; i >= 0; --i) {
ll cur = a[i] + rem * (ll)BASE;
a[i] = (int) (cur / v);
rem = (int) (cur % v);
}
trim();
}
BigInt operator/(int v) const {
if (llabs(v) >= BASE) return *this / BigInt(v);
BigInt res = *this;
res /= v;
return res;
}
void operator/=(const BigInt &v) {
*this = *this / v;
}
ll operator%(ll v) const {
int m = 0;
for (int i = a.size() - 1; i >= 0; --i) m = (a[i] + m * (ll) BASE) % v;
return m * sgn;
}
void operator*=(int v) {
if (llabs(v) >= BASE) {
*this *= BigInt(v);
return;
}
if (v < 0) sgn = -sgn, v = -v;
for (int i = 0, carry = 0; i < a.size() || carry; ++i) {
if (i == a.size()) a.push_back(0);
ll cur = a[i] * (ll) v + carry;
carry = (int) (cur / BASE);
a[i] = (int) (cur % BASE);
}
trim();
}
BigInt operator*(int v) const {
if (llabs(v) >= BASE) return *this * BigInt(v);
BigInt res = *this;
res *= v;
return res;
}
static std::vector<int> convert_base(const std::vector<int> &a, int old_digits, int new_digits) {
std::vector<ll> p(std::max(old_digits, new_digits) + 1);
p[0] = 1;
for (int i = 1; i < (int) p.size(); i++)
p[i] = p[i - 1] * 10;
std::vector<int> res;
ll cur = 0;
int cur_digits = 0;
for (int i = 0; i < (int) a.size(); i++) {
cur += a[i] * p[cur_digits];
cur_digits += old_digits;
while (cur_digits >= new_digits) {
res.push_back((ll)(cur % p[new_digits]));
cur /= p[new_digits];
cur_digits -= new_digits;
}
}
res.push_back((int) cur);
while (!res.empty() && !res.back())
res.pop_back();
return res;
}
void fft(std::vector<Cplx>& a, bool invert) const {
int n = a.size();
for (int i = 1, j = 0; i < n; ++i) {
int bit = n / 2;
for (; j >= bit; bit /= 2) j -= bit;
j += bit;
if (i < j) std::swap(a[i], a[j]);
}
for (int len = 2; len <= n; len *= 2) {
ld ang = 2 * PI / len * (invert ? -1 : 1);
Cplx wlen = polar(1, ang);
for (int i = 0; i < n; i += len) {
Cplx w(1);
for (int j = 0; j < len / 2; ++j) {
Cplx u = a[i + j], v = a[i + j + len / 2] * w;
a[i + j] = u + v;
a[i + j + len / 2] = u - v;
w *= wlen;
}
}
}
if (invert) for (int i = 0; i < n; ++i) a[i] /= n;
}
void multiply_fft(const std::vector<int> &a, const std::vector<int> &b, std::vector<int> &res) const {
std::vector<Cplx> fa(a.begin(), a.end()), fb(b.begin(), b.end());
int n = 1;
while (n < std::max(a.size(), b.size())) n *= 2;
n *= 2;
fa.resize(n);
fb.resize(n);
fft(fa, 0);
fft(fb, 0);
for (int i = 0; i < n; ++i) fa[i] *= fb[i];
fft(fa, 1);
res.resize(n);
ll carry = 0;
for (int i = 0; i < n; i++) {
ll t = (ll)(fa[i].real() + 0.5) + carry;
carry = t / FBASE;
res[i] = t % FBASE;
}
}
static inline int rev_incr(int a, int n) {
int msk = n / 2, cnt = 0;
while ( a & msk ) {
cnt++;
a <<= 1;
}
a &= msk - 1;
a |= msk;
while ( cnt-- ) a >>= 1;
return a;
}
static std::vector<Cplx> FFT(std::vector<Cplx> v, int dir = 1) {
Cplx wm, w, u, t;
int n = v.size();
std::vector<Cplx> V(n);
for (int k = 0, a = 0; k < n; ++k, a = rev_incr(a, n))
V[a] = v[k] / ld(dir > 0 ? 1 : n);
for (int m = 2; m <= n; m <<= 1) {
wm = polar( (ld)1, dir * 2 * PI / m );
for (int k = 0; k < n; k += m) {
w = 1;
for (int j = 0; j < m / 2; ++j, w *= wm) {
u = V[k + j];
t = w * V[k + j + m / 2];
V[k + j] = u + t;
V[k + j + m / 2] = u - t;
}
}
}
return V;
}
static void convolution(const std::vector<int>& a, const std::vector<int>& b, std::vector<int>& c) {
int sz = a.size() + b.size() - 1;
int n = 1 << int(ceil(log2(sz)));
std::vector<Cplx> av(n, 0), bv(n, 0), cv;
for (int i = 0; i < a.size(); i++) av[i] = a[i];
for (int i = 0; i < b.size(); i++) bv[i] = b[i];
cv = FFT(bv);
bv = FFT(av);
for (int i = 0; i < n; i++) av[i] = bv[i] * cv[i];
cv = FFT(av, -1);
c.resize(n);
ll carry = 0;
for (int i = 0; i < n; i++) {
ll t = ll(cv[i].real() + 0.5) + carry;
carry = t / FBASE;
c[i] = t % FBASE;
}
}
BigInt mul_simple(const BigInt &v) const {
BigInt res;
res.sgn = sgn * v.sgn;
res.a.resize(a.size() + v.a.size());
for (int i = 0; i < a.size(); i++) if (a[i])
for (int j = 0, carry = 0; j < v.a.size() || carry; j++) {
ll cur = res.a[i + j] + (ll) a[i] * (j < v.a.size() ? v.a[j] : 0) + carry;
carry = (int) (cur / BASE);
res.a[i + j] = (int) (cur % BASE);
}
res.trim();
return res;
}
BigInt mul_fft(const BigInt& v) const {
BigInt res;
convolution(convert_base(a, DIG, FDIG), convert_base(v.a, DIG, FDIG), res.a);
res.a = convert_base(res.a, FDIG, DIG);
res.trim();
return res;
}
void operator*=(const BigInt &v) {
*this = *this * v;
}
BigInt operator*(const BigInt &v) const {
if (1LL * a.size() * v.a.size() <= 1000111) return mul_simple(v);
return mul_fft(v);
}
BigInt abs() const {
BigInt res = *this;
res.sgn *= res.sgn;
return res;
}
void trim() {
while (!a.empty() && !a.back()) a.pop_back();
}
bool zero() const {
return a.empty() || (a.size() == 1 && !a[0]);
}
friend BigInt gcd(const BigInt &a, const BigInt &b) {
return b.zero() ? a : gcd(b, a % b);
}
};
BigInt power(BigInt a, ll k) {
BigInt ans = 1;
while (k > 0) {
if (k & 1) ans *= a;
a *= a;
k >>= 1;
}
return ans;
}
void solve(){
i64 n;std::cin >> n;
BigInt ans("1");
for(i64 i = 1;i<=5;++i){
ans = ans*(n-i+1)/i;
}
ans = ans*ans*120;
std::cout << ans << '\n';
}
int main(){
std::cin.tie(nullptr)->sync_with_stdio(false);
int t = 1;
// std::cin >> t;
for(int ti = 0;ti<t;++ti) {
solve();
}
return 0;
}
3.6 问题 F: 虎哥的有向图
我的代码
拓扑排序+dp
#include <bits/stdc++.h>
using i64 = long long;
using pii = std::pair<int,int>;
constexpr int N = 3e5+5,M = 1e6+5,INF = 0x3f3f3f3f;
int n,m;
std::string s;
std::vector<std::vector<int>> edges(N,std::vector<int>());
std::vector<int> indegrees(N,0);
std::vector<std::vector<int>> dp(N,std::vector<int>(30,0));
std::vector<int> v(N,0);
bool topo_sort() {
std::queue<int> q;
for(int i = 1;i<=n;++i) {
if(!indegrees[i]) q.emplace(i);
}
int sum = 0;
while(!q.empty()) {
auto t = q.front();
q.pop();
indegrees[t]=-1;
++sum;
for(int i = 0;i<edges[t].size();++i) {
int to = edges[t][i];
for(int j = 1;j<=26;++j) {
if(v[to]==j) {
dp[to][j] = std::max(dp[to][j],dp[t][j]+1);
}else {
dp[to][j] = std::max(dp[to][j],dp[t][j]);
}
}
if(!--indegrees[to]) {
q.emplace(to);
}
}
}
return sum==n;
}
void solve(){
std::cin >> n >> m >> s;
for(int i = 0;i<n;++i) {
v[i+1] = s[i]-'a'+1;
++dp[i+1][v[i+1]];
}
while(m--) {
int u,v;std::cin >> u >> v;
edges[u].emplace_back(v);
++indegrees[v];
}
if(topo_sort()) {
int ans = 0;
for(int i = 1;i<=n;++i) {
for(int j = 1;j<=26;++j) {
ans = std::max(ans,dp[i][j]);
}
}
std::cout << ans << '\n';
}else {
std::cout << "-1" << '\n';
}
}
int main(){
std::cin.tie(nullptr)->sync_with_stdio(false);
int t = 1;
// std::cin >> t;
for(int ti = 0;ti<t;++ti) {
solve();
}
return 0;
}
题解思路及代码
3.7 问题 G: 平安喜乐
我的代码
线段树,需要实现单点修改区间查询,
#include<bits/stdc++.h>
using namespace std;
using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;
#define cc(x) cout << fixed << setprecision(x)
#define int long long
#define ls u<<1
#define rs u<<1|1
template<class Node>
struct SegmentTree {
const int n, N;
vector<Node> tr;
SegmentTree(): n(0) {}
SegmentTree(int n_): n(n_), N(n * 4 + 10) {
tr.reserve(N);
tr.resize(N);
build(1, 1, n);
}
void build(int u, int l, int r) {
tr[u].l = l, tr[u].r = r;
tr[u].sum = 0; tr[u].tag = 0;
if (l == r) {
return;
}
int mid = (l + r) >> 1;
build(ls, l, mid);
build(rs, mid + 1, r);
}
void pushup(Node &T, Node L, Node R) {
T.l = L.l, T.r = R.r;
T.sum = L.sum + R.sum;
if (L.resr <= R.resl) {
T.sum += (L.r - L.R + 1) * (R.L - R.l + 1);
}
T.resl = L.resl, T.resr = R.resr;
T.L = (L.L == L.r && L.resr <= R.resl ? R.L : L.L);
T.R = R.R == R.l && R.resl >= L.resr ? L.R : R.R;
}
void update(int u, int id, int v) {
if (tr[u].l == tr[u].r ) {
tr[u].resl = tr[u].resr = v;
tr[u].sum = 1;
tr[u].L = tr[u].R = tr[u].l;
return;
}
int mid = (tr[u].l + tr[u].r) >> 1;
if (id <= mid) update(ls, id, v);
else update(rs, id, v);
pushup(tr[u], tr[ls], tr[rs]);
}
Node query(int u, int l, int r) {
if (tr[u].l >= l && tr[u].r <= r) return tr[u];
int mid = (tr[u].l + tr[u].r) >> 1;
if(r <= mid) return query(ls, l, r);
if(l > mid) return query(rs, l, r);
Node T;
pushup(T, query(ls, l, mid), query(rs, mid + 1, r));
return T;
}
};
struct Node {
int l, r;
int L, R, resl, resr;
int sum, tag;
};
constexpr int N = 2e5 + 10, M = N - 10;
void solve() {
int n, q;
cin >> n >> q;
SegmentTree<Node> tr(n);
vector<int> a(n + 1);
for (int i = 1; i <= n; i ++) {
cin >> a[i];
tr.update(1, i, a[i]);
}
while (q --) {
int op, l, r;
cin >> op >> l >> r;
if (op == 2) {
cout << tr.query(1, l, r).sum << '\n';
}
else {
a[l] = r;
tr.update(1, l, r);
}
}
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr), cout.tie(nullptr);
int T = 1;
// cin >> T;
while (T--) {
solve();
}
return 0;
}
迟点再把题解代码放上来 ,因为线段树写得很长,随意不方便直接截图
3.8 问题 H: 夜露死苦
我的代码写得有问题,虽然过了,但是是因为题目数据不够硬核,让我蒙混过去了,这里直接给题解的代码
原文地址:https://blog.csdn.net/Beau_Will/article/details/144096722
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