代码随想录算法训练营第28天 | 第八章 贪心算法03

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今日记录

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134.加油站

Leetcode链接

class Solution {
public:
    int canCompleteCircuit(vector<int>& gas, vector<int>& cost) {
        int curSum = 0;
        int totalSum = 0;
        int start = 0;
        for (int i = 0; i < gas.size(); i++) {
            curSum += gas[i] - cost[i];
            totalSum += gas[i] - cost[i];
            if (curSum < 0) {
                start = i + 1;
                curSum = 0;
            }
        }
        if (totalSum < 0)
            return -1;
        return start;
    }
};

135.分发糖果

Leetcode链接

class Solution {
public:
    int candy(vector<int>& ratings) {
        vector<int> candyVec(ratings.size(), 1);
        for (int i = 1; i < ratings.size(); i++) {
            if (ratings[i] > ratings[i - 1])
                candyVec[i] = candyVec[i - 1] + 1;
        }
        for (int i = ratings.size() - 2; i >= 0; i--) {
            if (ratings[i] > ratings[i + 1]) {
                candyVec[i] = max(candyVec[i], candyVec[i + 1] + 1);
            }
        }
        int result = 0;
        for (int i = 0; i < candyVec.size(); i++) {
            result += candyVec[i];
        }
        return result;
    }
};

860.柠檬水找零

Leetcode链接

class Solution {
public:
    bool lemonadeChange(vector<int>& bills) {
        vector<int> count(2, 0); // 手上5/10美元的数量
        if (bills[0] != 5)
            return false;
        else
            count[0]++;
        for (int i = 1; i < bills.size(); i++) {
            if (bills[i] == 5)
                count[0]++;
            if (bills[i] == 10) {
                count[0]--;
                count[1]++;
            }
            if (bills[i] == 20) {
                if (count[1] > 0) {
                    count[0]--;
                    count[1]--;
                } else {
                    count[0] -= 3;
                }
            }
            if (count[0] < 0 || count[1] < 0)
                return false;
        }
        return true;
    }
};

406.根据身高重建队列

Leetcode链接

class Solution {
public:
    static bool cmp(const vector<int>& a, const vector<int>& b) {
        if (a[0] == b[0])
            return a[1] < b[1];
        return a[0] > b[0];
    }
    vector<vector<int>> reconstructQueue(vector<vector<int>>& people) {
        sort(people.begin(), people.end(), cmp);
        vector<vector<int>> que;
        // people[i][1]的值代表前面有几个身高大于自己的人，将身高从大到小排列后，再按照k的值进行插值，k=2代表前面有两个身高达于自己的人，又因为前面身高就是从高到低排列，直接在que.begin()+k处插值保证了前面有多少身高大于自己的人
        for (int i = 0; i < people.size(); i++) {
            int position = people[i][1];
            que.insert(
                que.begin() + position,
                people[i]); // 在que.begin()+position处插入people[i]元素值
        }
        return que;
    }
};

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总结

原文地址：https://blog.csdn.net/monoki/article/details/140232029

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