1038. Recover the Smallest Number (30)

Given a collection of number segments, you are supposed to recover the smallest number from them. For example, given {32, 321, 3214, 0229, 87}, we can recover many numbers such like 32-321-3214-0229-87 or 0229-32-87-321-3214 with respect to different orders of combinations of these segments, and the smallest number is 0229-321-3214-32-87.

Input Specification:

Each input file contains one test case. Each case gives a positive integer N (<=10000) followed by N number segments. Each segment contains a non-negative integer of no more than 8 digits. All the numbers in a line are separated by a space.

Output Specification:

For each test case, print the smallest number in one line. Do not output leading zeros.

Sample Input:

5 32 321 3214 0229 87

Sample Output:

22932132143287

#include<cstdio>
#include<string>
#include<iostream>
#include<algorithm>
using namespace std;
bool cmp(string a, string b){
    return a + b < b + a;
}
string str[100010];
int main(){
    int n;
    cin >> n;
    for(int i = 0; i < n; i++){
        cin >> str[i];
    } 
    sort(str,str+n,cmp);
    string ans;
    for(int i = 0; i < n; i++){
        ans += str[i];
    } 
    while(ans.size() != 0 && ans[0] == '0'){
        ans.erase(ans.begin());
    }
    if(ans.size() == 0) cout << 0;
    else cout << ans;
}