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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. const int maxn = 400;
  4. const int maxval = 1e6;
  5. int a[maxn+5][maxn+5], m, n, pos[maxn*maxn+5][maxn+5], dp[maxn+5][maxn+5];
  6. vector <pair<int, int>> v[maxval+5];
  7. void read() {
  8.     cin >> m >> n;
  9.     for (int i = 1; i<=m; ++i) {
  10.         for (int j = 1; j<=n; ++j) {
  11.             cin >> a[i][j];
  12.             v[a[i][j]].push_back({i, j});
  13.         }
  14.     }
  15. }
  16. void solve() {
  17.     int cnt = 0;
  18.     for (int i = 1; i<=maxval; ++i) {
  19.         if (!v[i].empty()) {
  20.             for (auto p : v[i]) {
  21.                 a[p.first][p.second] = cnt;
  22.             }
  23.             ++cnt;
  24.         }
  25.     }
  26.     int ans = 0;
  27.     for (int k = 1; k<=m; ++k) {
  28.         for (int i = n; i>=1; --i) {
  29.             for (int j = i; j<=n; ++j) {
  30.                 dp[i][j] = max({dp[i][j], dp[i+1][j], dp[i][j-1], pos[a[k][i]][i], pos[a[k][j]][j]});
  31.                 if (i < j) {
  32.                     dp[i][j] = max({dp[i][j], pos[a[k][i]][j], pos[a[k][j]][i]});
  33.                     if (a[k][i] == a[k][j]) dp[i][j] = k;
  34.                 }
  35.                 ans = max(ans, (j-i+1) * (k - dp[i][j]));
  36.             }
  37.         }
  38.         for (int i = 1; i<=n; ++i) {
  39.             pos[a[k][i]][i] = k;
  40.         }
  41.     }
  42.     cout << ans;
  43. }
  44. int main() {
  45.     ios_base::sync_with_stdio(false);
  46.     cin.tie(0); cout.tie(0);
  47.     read();
  48.     solve();
  49.     return 0;
  50. }
  51.  
Success #stdin #stdout 0.01s 28284KB
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stdin 
Standard input is empty
stdout 
Standard output is empty
https://ideone.com/XcqMcw
language:
C++ (gcc 8.3)
created:
1 day ago
visibility:
public

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