633. Sum of Square Numbers

Given a non-negative integer 

c

a

b

Example 1:

Input: 5
Output: True
Explanation: 1 * 1 + 2 * 2 = 5

Example 2:

Input: 3
Output: False


判断c是否为a^2+b^2

C++(3ms):

1 class Solution {
2 public:
3     bool judgeSquareSum(int c) {
4         int left = 0 ;
5         int right = (int)sqrt(c) ;
6         while(left <= right){
7             int cur = left*left + right*right ;
8             if (cur == c){
9                 return true ;
10             }else if (cur < c){
11                 left++ ;
12             }else{
13                 right-- ;
14             }
15         }
16         return false ;
17     }
18 };

java(14ms):

1 class Solution {
2     public boolean judgeSquareSum(int c) {
3         int left = 0 ;
4         int right = (int)Math.sqrt(c) ;
5         while(left <= right){
6             int cur = left*left + right*right ;
7             if (cur == c){
8                 return true ;
9             }else if (cur < c){
10                 left++ ;
11             }else{
12                 right-- ;
13             }
14         }
15         return false ;
16     }
17 }