PAT (Advanced) 1038. Recover the Smallest Number (30)

#include <iostream>#include <string>#include <vector>#include <algorithm>using namespace std;bool cmp(const string &a, const string &b){return (a + b) < (b + a);}int main(){int n;cin >> n;vector<string> num(n);for (int i = 0; i < n; i++){cin >> num[i];}sort(num.begin(), num.end(), cmp);string result;for (int i = 0; i < n; i++){result += num[i];}int i;for (i = 0; i < result.size() && result[i] == '0'; i++);if (i == result.size())cout << 0 << endl;elsecout << result.substr(i) << endl;}