Codeforces 777D：Cloud of Hashtags（水题）

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 string s[500010];
 4 string ans[500010];
 5 int main() {
 6     int n;
 7     scanf("%d", &n);
 8     for(int i = 1; i <= n; i++) cin >> s[i];
 9     ans[n] = s[n];
10     for(int i = n - 1, j; i >= 1; i--) {
11         if(ans[i+1] >= s[i]) { ans[i] = s[i]; continue; }
12 
13         int a = s[i].size(), b = ans[i+1].size();
14         int len = min(a, b);
15         for(j = 0; j < len; j++)
16             if(s[i][j] > ans[i+1][j]) break;
17         for(int k = 0; k < j; k++) ans[i] += s[i][k];
18     }
19     for(int i = 1; i <= n; i++) cout << ans[i] << endl;
20     return 0;
21 }