package algo.dp;
import java.util.Arrays;
/**
* Created by sherxon on 3/14/17.
*/
public class SubsetSum {
/**
* This is DP solution for subsetSum problem. Time complexity is O(n*m)
*/
boolean subsetSum2(int[] set, int sum) {
boolean[][] a = new boolean[set.length][sum + 1];
Arrays.sort(set);
a[0][set[0]] = true;
for (int i = 1; i < a.length; i++) {
a[i - 1][0] = true;
for (int j = 1; j < a[i].length; j++) {
if (j < set[i])
a[i][j] = a[i - 1][j];
else
a[i][j] = a[i - 1][j] || a[i - 1][j - set[i]];
}
}
return a[set.length - 1][sum];
}
/**
* This is brute force solution to find subset Sum.
* Time Complexity is O(n^2) and Space Complexity is O(1);
*/
boolean subsetSum(int[] a, int n, int k) {
if (k == 0) return true;
if (n == 0) return false;
if (a[n - 1] > k) return subsetSum(a, n - 1, k);
return subsetSum(a, n - 1, k) || subsetSum(a, n - 1, k - a[n - 1]);
}
}