leetcode 122. Best Time to Buy and Sell Stock II

题目122. Best Time to Buy and Sell Stock II
标签： 贪心

思路

找到除了第一个点的所有峰值，然后，对于每一个峰值，减去与前一个峰值（包括第一个点，如果它也是峰值的话）之间的山谷值得到差值，将所有的差值加起来就是最大收益

实现

# include <iostream># include <vector>using namespace std;class Solution {public:    int maxProfit(vector<int>& prices) {       int size = prices.size();       if(size <= 1) return 0;       int ret = 0;       int last_max = -1, last_min = prices[0];       for(int i = 1; i < size; i++) {            if(prices[i] <= last_min && last_max == -1) last_min = prices[i];            else if(prices[i] > last_min && prices[i] >= last_max) last_max = prices[i];            else { // get a valid and best last_min and last_max                ret += last_max - last_min;                last_min = prices[i];                last_max = -1;                      }        }        // the last case        if(last_max != -1) ret += last_max - last_min;        return ret;    }};