[luoguP1169] [ZJOI2007]棋盘制作（单调栈）

传送门

和玉蟾宫差不多

——代码

 #include <cstdio>
 #include <iostream>

 using namespace std;

 const int MAXN = ;
 int n, m, ans1, ans2, top;
 int a[MAXN][MAXN][], s[MAXN], r[MAXN], l[MAXN];

 inline void work(int k)
 {
     int i, j;
     for(i = ; i <= ; i++)
     {
         a[k][][i] = a[k][m + ][i] = -;
         top = ;
         for(j = ; j <= m + ; j++)
         {
             while(top && a[k][s[top]][i] > a[k][j][i]) r[s[top--]] = j;
             s[++top] = j;
         }
         top = ;
         for(j = m; j >= ; j--)
         {
             while(top && a[k][s[top]][i] > a[k][j][i]) l[s[top--]] = j;
             s[++top] = j;
         }
         for(j = ; j <= m; j++)
         {
             ans1 = max(ans1, min(a[k][j][i], r[j] - l[j] - ) * min(a[k][j][i], r[j] - l[j] - ));
             ans2 = max(ans2, a[k][j][i] * (r[j] - l[j] - ));
         }
     }
 }

 int main()
 {
     int i, j, x;
     scanf("%d %d", &n, &m);
     for(i = ; i <= n; i++)
         for(j = ; j <= m; j++)
         {
             scanf("%d", &x);
             if((i + j) % ) x ^= ;
             a[i][j][x] = a[i - ][j][x] + ;
         }
     for(i = ; i <= n; i++) work(i);
     printf("%d\n%d\n", ans1, ans2);
     return ;
 }