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