Winning Lottery-Greedy Problem Coding Ninjas CP Course

Winning Lottery
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Harshit knows through his resources that this time the winning lottery number is the smallest number whose sum of the digits is S and the number of digits is D. You have to help Harshit and print the winning lottery number.
Input Format:
First line of input contians an integer T, representing the number of test cases.
Next T lines contains two space-separated integers: S,D
Constraints:
1 <= T <= 1000
1 <= D <= 1000
1 <= S <= 9*D
Time Limit: 1 second
Output Format
The output contains a single integer denoting the winning lottery number
Sample Input 1:
1
9 2
Sample Output 1:
18
Explanation
There are many other possible numbers like 45, 54, 90, etc with the sum of digits as 9 and number of digits as 2. The smallest of them is 18.

#include<bits/stdc++.h>
using namespace std;
int main(){
    
    // write your code here
    int t;cin>>t;
    while(t--){
        int s,d;cin>>s>>d;
        int arr[d]={0};
        arr[0]=1;
        int temp=d;
        s-=1;
        while(s>0){
            while(temp>=0){
                if(s>=9){
                    arr[temp-1]+=9;
                    s-=9;
                }
                else{
                    arr[temp-1]+=s;
                    s=0;
                }
                temp--;
            }
        }
        for(int i=0;i<d;i++){
            cout<<arr[i];
        }
        cout<<endl;
    }
    return 0;
}