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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. string s;
  5. unordered_map<string,string> memo;
  6.  
  7. bool isRepeat(const string &t, string &sub, int &cnt) {
  8.     int n = t.size();
  9.     for (int len = 1; len <= n/2; len++) {
  10.         if (n % len != 0) continue;
  11.         string x = t.substr(0, len);
  12.         bool ok = true;
  13.         for (int i = len; i < n; i += len) {
  14.             if (t.substr(i, len) != x) { ok = false; break; }
  15.         }
  16.         if (ok) {
  17.             sub = x;
  18.             cnt = n / len;
  19.             return true;
  20.         }
  21.     }
  22.     return false;
  23. }
  24.  
  25. string solve(string t) {
  26.     if (memo.count(t)) return memo[t];
  27.     int n = t.size();
  28.     if (n == 0) return "";
  29.     if (n == 1) return t;
  30.  
  31.     string best = t; // raw
  32.  
  33.     // thử nén bằng dạng k(sub)
  34.     string sub;
  35.     int cnt;
  36.     if (isRepeat(t, sub, cnt)) {
  37.         string subEnc = solve(sub);
  38.         string cand = to_string(cnt) + "(" + subEnc + ")";
  39.         if (cand.size() < best.size()) best = cand;
  40.     }
  41.  
  42.     // thử cắt t thành 2 phần bất kì và nén riêng từng phần
  43.     for (int i = 1; i < n; i++) {
  44.         string left = solve(t.substr(0, i));
  45.         string right = solve(t.substr(i));
  46.         string cand = left + right;
  47.         if (cand.size() < best.size()) best = cand;
  48.     }
  49.  
  50.     return memo[t] = best;
  51. }
  52.  
  53. int main() {
  54.         freopen("wstring.inp", "r", stdin);
  55.     freopen("wstring.out", "w", stdout);
  56.     int n; cin >> n;    
  57.     cin >> s;
  58.     cout << solve(s);
  59. }
  60.  
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
https://ideone.com/9kD3PR
language:
C++ (gcc 8.3)
created:
1 day ago
visibility:
public

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