代码随想录算法训练营第31天｜455. 分发饼干，376. 摆动序列，53. 最大子数组和

Day 31

455. 分发饼干

class Solution {
public:
    int findContentChildren(vector& g, vector& s) {
        sort(g.begin(), g.end());
        sort(s.begin(), s.end());
        int m = g.size(), n = s.size();
        int count = 0;
        for (int i = 0, j = 0; i < m && j < n; i++, j++) {
            while (j < n && g[i] > s[j]) {
                j++;
            }
            if (j < n) {
                count++;
            }
        }
        return count;
    }
};

java版：

class Solution {
    public int findContentChildren(int[] g, int[] s) {
        Arrays.sort(g);
        Arrays.sort(s);
        int m = g.length, n = s.length;
        int count = 0;
        for (int i = 0, j = 0; i < m && j < n; i++, j++) {
            while (j < n && g[i] > s[j]) {
                j++;
            }
            if (j < n) {
                count++;
            }
        }
        return count;
    }
}

376. 摆动序列

class Solution {
public:
    int wiggleMaxLength(vector& nums) {
        int n = nums.size();
        if (n < 2) {
            return n;
        }
        int up = 1, down = 1;
        for (int i = 1; i < n; i++) {
            if (nums[i] > nums[i - 1]) {
                up = max(up, down + 1);
            } else if (nums[i] < nums[i - 1]) {
                down = max(up + 1, down);
            }
        }
        return max(up, down);
    }
};

java版：

class Solution {
    public int wiggleMaxLength(int[] nums) {
        int n = nums.length;
        if (n < 2) {
            return n;
        }
        int[] up = new int[n];
        int[] down = new int[n];
        up[0] = down[0] = 1;
        for (int i = 1; i < n; i++) {
            if (nums[i] > nums[i - 1]) {
                up[i] = Math.max(up[i - 1], down[i - 1] + 1);
                down[i] = down[i - 1];
            } else if (nums[i] < nums[i - 1]) {
                up[i] = up[i - 1];
                down[i] = Math.max(up[i - 1] + 1, down[i - 1]);
            } else {
                up[i] = up[i - 1];
                down[i] = down[i - 1];
            }
        }
        return Math.max(up[n - 1], down[n - 1]);
    }
}

53. 最大子数组和

class Solution {
public:
    int maxSubArray(vector& nums) {
        int pre = 0, maxAns = nums[0];
        for (const auto &x: nums) {
            pre = max(pre + x, x);
            maxAns = max(maxAns, pre);
        }
        return maxAns;
    }
};

java版：

class Solution {
    public int maxSubArray(int[] nums) {
        int pre = 0, maxAns = nums[0];
        for (int x : nums) {
            pre = Math.max(pre + x, x);
            maxAns = Math.max(maxAns, pre);
        }
        return maxAns;
    }
}