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Leetcode P0069"Sqrt(x)" 题解

2020/08/28 Leetcode

博文中会简要介绍Leetcode P0069题目分析及解题思路。

“Sqrt(x)”是一道灵活运用二分查找的问题，二分查找平方根即可。

Implement int sqrt(int x).

Compute and return the square root of x, where x is guaranteed to be a non-negative integer.

Since the return type is an integer, the decimal digits are truncated and only the integer part of the result is returned.

以下是Java的题解代码实现。

class Solution {
    public int mySqrt(int x) {
        if (x <= 1)
            return x;
        
        int left = 0, right = x;
        long mid = 0;
        while (left <= right) {
            mid = (left+right)/2;
            
            if (mid*mid > x)
                right = (int) mid-1;
            else if (mid*mid < x)
                left = (int) mid+1;
            else
                return (int) mid;
        }
        
        return (mid*mid > x)? (int) mid-1: (int) mid;
    }
}
Java

以下是C++的题解代码实现。

class Solution {
public:
    int mySqrt(int x) {
        if (x <= 1)
            return x;
        
        int left = 0, right = x;
        long mid = 0;
        while (left <= right) {
            mid = (left+right)/2;
            
            if (mid*mid > x) 
                right = mid-1;
            else if (mid*mid < x)
                left = mid+1;
            else 
                return mid;
        }
        
        return (mid*mid > x)? mid-1: mid;
    }
};
C++

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