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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. const int maxn = 405;
  6. const int maxval = 1e6;
  7.  
  8. int pos[maxn*maxn+5][maxn+5], dp[maxn+5][maxn+5], a[maxn+5][maxn+5];
  9. vector<pair<int, int>> v[maxval+5];
  10. int n, m;
  11. void read() {
  12.     cin >> m >> n;
  13.     for (int i = 1; i<=m; ++i) {
  14.         for (int j = 1; j<=n; ++j) cin >> a[i][j];
  15.     }
  16. }
  17. void solve() {
  18.     for (int i = 1; i <= m; ++i) {
  19.         for (int j = 1; j <= n; ++j)
  20.             v[a[i][j]].push_back({i, j}); //val.push_back
  21.     }
  22.     int cnt = 0;
  23.     for (int i = 1; i < maxval; ++i) {
  24.         for (auto p : v[i])
  25.             a[p.first][p.second] = cnt;
  26.         if (!v[i].empty()) ++cnt;
  27.     }
  28.     int ans = 0;
  29.     for (int k = 1; k <= m; ++k) {
  30.         for (int i = n; i >= 1; --i) {
  31.             for (int j = i; j <= n; ++j) {
  32.                 dp[i][j] = max({dp[i][j], pos[a[k][i]][i], pos[a[k][j]][j],
  33.                            dp[i+1][j], dp[i][j-1]});
  34.  
  35.                 if (i < j) {
  36.                     dp[i][j] = max({dp[i][j], pos[a[k][i]][j], pos[a[k][j]][i]});
  37.                     if (a[k][i] == a[k][j]) dp[i][j] = k;
  38.                 }
  39.  
  40.                 ans = max(ans, (j - i + 1) * (k - dp[i][j]));
  41.             }
  42.         }
  43.         for (int i = 1; i <= n; ++i)
  44.             pos[a[k][i]][i] = k;
  45.     }
  46.  
  47.     cout << ans;
  48. }
  49. int main() {
  50.     ios_base::sync_with_stdio(0);
  51.     cin.tie(0); cout.tie(0);
  52.     read();
  53.     solve();
  54.     return 0;
  55. }
  56.  
Success #stdin #stdout 0.01s 28324KB
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https://ideone.com/PkXm6Q
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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