代码随想录day37

738单调递增的数字

class Solution {
public:
    int monotoneIncreasingDigits(int N) {
        string strNum = to_string(N);
        int flag = strNum.size();
        for (int i = strNum.size() - 1; i > 0; i--) 
        {
            if (strNum[i - 1] > strNum[i] ) {
                flag = i;
                strNum[i - 1]--;
            }
        }
        for (int i = flag; i < strNum.size(); i++) {
            strNum[i] = '9';
        }
        return stoi(strNum);
    }
};

968监控二叉树

class Solution {
private:
    int result;
    int traversal(TreeNode* cur) 
    {
        if (cur == NULL) return 2;
        int left = traversal(cur->left);    
        int right = traversal(cur->right); 

        if (left == 2 && right == 2) return 0;
        else if (left == 0 || right == 0) 
        {
            result++;
            return 1;
        }
        else return 2;
    }

public:
    int minCameraCover(TreeNode* root) {
        result = 0;
        if (traversal(root) == 0) 
        { 
            result++;
        }
        return result;
    }
};