lintcode: Check Sum of Square Numbers

Check Sum of Square Numbers

Given a integer c, your task is to decide whether there're two integers a and b such that a^2 + b^2 = c.

您在真实的面试中是否遇到过这个题？

Yes

样例

Given n = 5
Return true // 1 * 1 + 2 * 2 = 5

Given n = -5
Return false

代码

 class Solution {
 public:
     /*
      * @param : the given number
      * @return: whether whether there're two integers
      */
     bool checkSumOfSquareNumbers(int num) {
         // write your code here
         if (num < ) {
             return false;
         }
         int c = floor(sqrt(num));
         int i = c;
         if (i * i == num) return true;
         int j = ;
         while (j <= i) {
             if (i * i + j * j == num) {
                 return true;
             } else if (i * i + j * j < num) {
                 j++;
             } else {
                 i--;
             }
         }
         return false;
     }
 };