weixin_38783585的博客

import java.util.ArrayList;import java.util.Stack;import java.util.Collections;/**public class TreeNode {    int val = 0;    TreeNode left = null;    TreeNode right = null;    public TreeNode(int val)...

method1 simple but not allow public boolean isPerfectSquare(int num) { int sqrt = (int) Math.sqrt(num); return sqrt * sqrt == num; } method2 newto method public boolean isP...

this is a binary search problem. code show as below: public class Solution extends GuessGame { public int guessNumber(int n) { int left = 1, right = n; while (left < right) { ...