题解 | #求平方根#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param x int整型 
     * @return int整型
     */
    public int mysqrt (int x) {
        // write code here
        long ret = 0;
        int left = 1;
        int right = x;
        long num = 0;
        for (;left <= right;){
            ret = (left + right) / 2;
            if ((ret*ret) < x){
                if (((ret+1) * (ret+1)) > x){
                    break;
                }
                left = (int)ret + 1;
            }else if ((ret*ret) > x){
                if (((ret-1) * (ret-1)) < x){
                    ret--;
                    break;
                }
                right = (int)ret - 1;
            }else if((ret*ret) == x){
                break;
            }
        }
        return (int)ret;
    }
}