Perfect Square

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.

public class Solution {
    public int numSquares(int n) {
        int[] dp  = new int[n+1]; //from 0 to n 
        dp[0] = 0; 
        for (int i = 1; i <= n; i++) {
            int min = Integer.MAX_VALUE; 
            int j = 1; 
            while (i - j*j >= 0) {
                min = Math.min(min, dp[i-j*j]+1);
                j++; 
            }
            dp[i] = min; 
        }
        return dp[n];
    }
}
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s