Combination SumIV 不难最好bug free 面试官可能让你还要用DP实现 dp在其它post中

public static int DFS(int[] nums, int target) {
if (target == 0) {
return 1;
}
int res = 0;
for (int i = 0; i < nums.length; i++) {
if (target >= nums[i]) {
res += DFS(nums, target - nums[i]);
}
}
return res;
}