738.單調遞增的數字
題目鏈接：738.單調遞增的數字
文檔鏈接：738.單調遞增的數字
視頻鏈接：貪心算法，思路不難想，但代碼不好寫！LeetCode:738.單調自增的數字
C++實現
class Solution {
public:int monotoneIncreasingDigits(int n) {string num = to_string(n);int flag = num.size();for (int i = num.size() - 1; i > 0; i--) {if (num[i] < num[i - 1]) {flag = i;num[i - 1]--;}}for (int i = flag; i < num.size(); i++) {num[i] = '9';}return stoi(num);}
};
968.監控二叉樹
題目鏈接：968.監控二叉樹
文檔鏈接：968.監控二叉樹
視頻鏈接：貪心算法，二叉樹與貪心的結合，有點難… LeetCode:968.監督二叉樹
C++實現
class Solution {
private:int result = 0;int backtracking(TreeNode* node) {if (node == NULL)return 2;int left = backtracking(node->left);int right = backtracking(node->right);if (left == 2 && right == 2)return 0;if (left == 0 || right == 0) {result++;return 1;}if (left == 1 || right == 1)return 2;return -1;}public:int minCameraCover(TreeNode* root) {result = 0;int n = backtracking(root);if (n == 0)result++;return result;}
};
)
