Codeforces Round #277.5 (Div. 2), problem: (C) Given Length and Sum of Digits..

Greedy
特例真多

#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<cstring>
#include<vector>
#include<utility>
#include<map>
#include<set>
#include<queue>
#include<cmath>
using namespace std;
typedef long long int int64;
int main()
{
    int n, sum;
    scanf("%d %d", &n, &sum);
    if(sum == 0 and n == 1){
        puts("0 0");
        return 0;
    }
    if(sum == 0 or sum > n*9){
        puts("-1 -1");
        return 0;
    }
    int psum = sum;
    int arr[101] = {0};
    arr[n-1] = 1; psum--;
    for(int lx = 0;lx < n;lx++){
        if(psum >= 9){
            arr[lx] += 9;
            psum -= 9;
        }else{
            arr[lx] += psum;
            psum = 0;
        }
    }
    for(int lx = n-1;lx >= 0;lx--)
        printf("%d", arr[lx]);
    printf(" ");
    for(int lx = 0;lx < sum/9;lx++)
        printf("9");
    if(sum/9<n){
        printf("%d", sum%9);
        for(int lx = sum/9+1;lx < n;lx++)
            printf("0");
    }
    printf("\n");

    return 0;
}