PAT 1038. Recover the Smallest Number (30)

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 <iostream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

bool cmp(const string& s1, const string& s2)
{
    return s1 + s2 < s2 + s1;
}

int main()
{
    int segNum;
    vector<string> segment;
    cin >> segNum;
    for (int i = 0; i < segNum; i++)
    {
        string seg;
        cin >> seg;
        segment.push_back(seg);
    }
    sort(segment.begin(), segment.end(), cmp);
    string res;
    for (int i = 0; i < segment.size(); i++)
        res += segment[i];

    string::iterator it = res.begin();
    while (*it == '0')
        it = res.erase(it);

    if (res.empty())
        cout << "0";
    else
        cout << res;
}