Find the number of permutations

Here you are Different An array of integers nums , And a target integer target . Please start from nums Find and return the sum of target The number of element combinations of .

The data of the questions ensure that the answers are in line with 32 Bit integer range .

Example 1：
Input ：nums = [1,2,3], target = 4 Output ：7 explain ： All possible combinations are ：
(1, 1, 1, 1)
(1, 1, 2)
(1, 2, 1)
(1, 3)
(2, 1, 1)
(2, 2)
(3, 1)
Please note that , Different sequences are considered as different combinations .

Example 2：

Input ：nums = [9], target = 3 Output ：0

Code

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];
    }
}