[leetcode 279]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 .
Credits: Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.
ACコード:

class Solution
{
public:
    int numSquares(int n)
    {
        int least[n+1];
        memset(least,0,sizeof(least));
        for(int i=1;i<=n;++i)
        {
                least[i]=i;
                for(int j=1;j*j<=i;++j)
                {
                    if(j*j==n)
                        least[i]=1;
                    else
                        least[i]=least[i-j*j]+1<least[i]?least[i-j*j]+1:least[i];
                }
        }
        return least[n];
    }
};