Leetcode186: Perfect Squares

Given a positive integer n, find the least number of perfect square numbers (for example,

1,
4, 9, 16, ...

) which sum to n.

For example, given n =

12

, return

3

because

12
= 4 + 4 + 4

; given n =

13

, return

2

because

13
= 4 + 9

.

class Solution {
public:
int numSquares(int n) {
int *dp = new int[n+1];
for(int i = 0; i <= n; i++)
{
dp[i]=i;
for(int j = sqrt(i); i-j*j>=0; j--)
{
if(dp[i-j*j]+1 < dp[i])
dp[i] = dp[i-j*j]+1;
}
}
return dp
;
}
};