leetcode打卡#day34 455. 分发饼干、376. 摆动序列、53. 最大子数组和

455. 分发饼干

class Solution {
public:
    int findContentChildren(vector<int>& g, vector<int>& s) {
        //胃口排序
        sort(g.begin(), g.end());
        //蛋糕排序
        sort(s.begin(), s.end());
        //能满足孩纸的数量
        int count = 0;
        for (int i = 0, j = 0; i < g.size()&&j < s.size(); ) {
            if (s[j] >= g[i]) {
                j++;
                i++;
                count++;
            }else {
                j++;
            }
        }
        return count;
    }
};

376. 摆动序列

class Solution {
public:
    int wiggleMaxLength(vector<int>& nums) {
        int cur;//当前2个数需要的差值为正数/负数, 正数为1，负数为0
        int count = 1; //摆动序列的最大长度,初始为1
        int tmp; //记录当前数与上一个数差正负
        if (nums.size() <= 1) return nums.size();// <=1直接输出
        for (int i = 1; i < nums.size(); i++) {
            tmp = nums[i]-nums[i-1];
            //差值>0才符合摆动条件
            if (abs(tmp) > 0) {
                if (count == 1) {
                    cur = tmp > 0 ? 0:1;
                    count++;
                //cur > 0 && 当前差 > 0
                }else if (cur == 1 && tmp > 0) {
                    cur = 0;
                    count++;
                //cur < 0 && 当前差 < 0
                }else if (cur == 0 && tmp < 0){
                    cur = 1;
                    count++;
                }
            }
        }
        return count;
    }
};

53. 最大子数组和

class Solution {
public:
    int maxSubArray(vector<int>& nums) {
        int n = nums.size();
        int maxRes = nums[0];
        for(int i = 1; i < n; i++){
            if(nums[i-1] > 0) {
                nums[i] = nums[i-1]+nums[i];
            }
            maxRes = max(maxRes,nums[i]);
        }
        return maxRes;
    }
};