Combination Sum IV.java

/*
    Given an integer array with all positive numbers and no duplicates, find the number of 
    possible combinations that add up to a positive integer target.
    
    Link: https://leetcode.com/problems/combination-sum-iv/

    Example:
        nums = [1, 2, 3]
		target = 4

		The possible combination ways are:
		(1, 1, 1, 1)
		(1, 1, 2)
		(1, 2, 1)
		(1, 3)
		(2, 1, 1)
		(2, 2)
		(3, 1)

		Note that different sequences are counted as different combinations.
		Therefore the output is 7.

    Solution: None

    Source: https://leetcode.com/problems/combination-sum-iv/
*/

public class Solution {
    public int combinationSum4(int[] nums, int target) {
        int[] comb = new int[target + 1];
        comb[0] = 1;
        for (int i = 1; i < comb.length; i++) {
            for (int j = 0; j < nums.length; j++) {
                if (i - nums[j] >= 0) {
                    comb[i] += comb[i - nums[j]];
                }
            }
        }
        return comb[target];
    }
}