Concatenate all strings to produce the smallest lexicographic string

Concatenate all strings to produce the smallest lexicographic string

Title description

Given a string array strs, please find a splicing order so that the string composed of all the strings is the smallest lexicographical order among all possibilities, and return this string.

Enter a description:

The input contains multiple lines, the first line contains an integer $n(1\le n\le 10^5)$, represents the length of the string array strs, the next n lines, each line has a string, representing strs[i] (ensure that the length of all strings is less than 10).

Output description:

Output one line, containing a string, representing the string with the smallest lexicographic order returned.

Example 1

enter

2
abc
de

Output

abcde

Example 2

enter

2
b
ba

Output

bab

---

answer:

Greedy, define a comparator and concatenate it after sorting:

If str1+str2 <= str2+str1, then str1 is placed at the front, otherwise placed at the back. The proof of the specific greedy strategy can be seen in this part of the book.

Code:

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

using namespace std;

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

int main(void) {
    
    
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    int n;
    cin >> n;
    string s;
    vector<string> v;
    while (n--) {
    
    
        cin >> s;
        v.push_back(s);
    }
    sort(v.begin(), v.end(), cmp);
    for (auto it : v)
        cout << it;
    cout << endl;
    return 0;
}