```
int combinationSum4(vector<int>& nums, int target) {
vector<int> dp(target+1,0);
dp[0]=1;
for(int i=1;i<=target;i++){
for(int j=0;j<nums.size();j++){
if(i>=nums[j]){
dp[i]+=dp[i-nums[j]];
}
}
}
return dp[target];
}
```