Language: C

#include <stdio.h>
#define MAX 200000
int func(int a, int b, int c, int d, int dp[19][19][19][19]);
int min4(int a, int b, int c, int d);

int min(int a, int b);
int main()
{
    int h, w;
    long maxi;
    char S[21][21];
    int dp[19][19][19][19] = 0;
    scanf("%d %d", &h, &w);
    for (int i = 0; i < h; i++)
    {
        for (int j = 0; j < w; j++)
        {
            scanf("%c", &S[i][j]);
        }
    }
    for (int i = 0; i < h; i++)
    {
        for (int j = 0; j < w; j++)
        {
            if (i == 19)
            {
                dp[i][j][i][j + 1] = 1;
            }
            else if (j == 19)
            {
                dp[i][j][i + 1][j] = 1;
            }
            else
            {
                dp[i][j][i + 1][j] = 1;
                dp[i][j][i][j + 1] = 1;
            }
        }
    }
    int k = 0;
    for (int i = 0; i < 20; i++)
    {
        for (int j = 0; j < 20; j++)
        {
            for (int c = i; c < 20; c++)
            {
                for (int d = j; d < 20; d++)
                {
                    k = func(i, j, c, d, dp[19][19][19][19]);
                    if (k > maxi)
                    {
                        maxi = k;
                    }
                }
            }
        }
    }
    printf("%ld", maxi);
    return 0;
}

int func(int a, int b, int c, int d, int dp[19][19][19][19])
{
    if (dp[a][b][c][d] == 0)
    {
        dp[a][b][c][d] = 1;
        if (c == 0 & d == 0)
        {
            dp[a][b][c][d] += min(func(a, b, c + 1, d, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19]));
        }
        else if (c == 19 && d == 19)
        {
            dp[a][b][c][d] += min(func(a, b, c - 1, d, dp[19][19][19][19]), func(a, b, c, d - 1, dp[19][19][19][19]));
        }
        else if (c == 0)
        {
            dp[a][b][c][d] += min(func(a, b, c, d - 1, dp[19][19][19][19]), min(func(a, b, c + 1, d, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19])));
        }
        else if (d == 0)
        {
            dp[a][b][c][d] += min(func(a, b, c - 1, d, dp[19][19][19][19]), min(func(a, b, c + 1, d, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19])));
        }
        else if (c == 19)
        {
            dp[a][b][c][d] += min(func(a, b, c, d + 1, dp[19][19][19][19]), min(func(a, b, c - 1, d, dp[19][19][19][19]), func(a, b, c, d - 1, dp[19][19][19][19])));
        }
        else if (d == 19)
        {
            dp[a][b][c][d] += min(func(a, b, c + 1, d, dp[19][19][19][19]), min(func(a, b, c - 1, d, dp[19][19][19][19]), func(a, b, c, d - 1, dp[19][19][19][19])));
        }
        else
        {
            dp[a][b][c][d] += min4(func(a, b, c, d - 1, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19]), func(a, b, c - 1, d, dp[19][19][19][19]), func(a, b, c + 1, d, dp[19][19][19][19]));
        }
    }
    return dp[a][b][c][d];
}

int min4(int a, int b, int c, int d)
{
    int min1, min2;
    min1 = min(a, b);
    min2 = min(c, d);
    return min(min1, min2);
}
int min(int a, int b)
{
    return (a < b) ? a : b;
}

Compiler output:
main.c: In function 'main':
main.c:12:30: error: invalid initializer
   12 |     int dp[19][19][19][19] = 0;
      |                              ^
main.c:49:56: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   49 |                     k = func(i, j, c, d, dp[19][19][19][19]);
      |                                          ~~~~~~~~~~~~~~^~~~
      |                                                        |
      |                                                        int
main.c:3:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
    3 | int func(int a, int b, int c, int d, int dp[19][19][19][19]);
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c: In function 'func':
main.c:69:70: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   69 |             dp[a][b][c][d] += min(func(a, b, c + 1, d, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19]));
      |                                                        ~~~~~~~~~~~~~~^~~~
      |                                                                      |
      |                                                                      int
main.c:62:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
   62 | int func(int a, int b, int c, int d, int dp[19][19][19][19])
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c:69:112: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   69 |             dp[a][b][c][d] += min(func(a, b, c + 1, d, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19]));
      |                                                                                                  ~~~~~~~~~~~~~~^~~~
      |                                                                                                                |
      |                                                                                                                int
main.c:62:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
   62 | int func(int a, int b, int c, int d, int dp[19][19][19][19])
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c:73:70: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   73 |             dp[a][b][c][d] += min(func(a, b, c - 1, d, dp[19][19][19][19]), func(a, b, c, d - 1, dp[19][19][19][19]));
      |                                                        ~~~~~~~~~~~~~~^~~~
      |                                                                      |
      |                                                                      int
main.c:62:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
   62 | int func(int a, int b, int c, int d, int dp[19][19][19][19])
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c:73:112: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   73 |             dp[a][b][c][d] += min(func(a, b, c - 1, d, dp[19][19][19][19]), func(a, b, c, d - 1, dp[19][19][19][19]));
      |                                                                                                  ~~~~~~~~~~~~~~^~~~
      |                                                                                                                |
      |                                                                                                                int
main.c:62:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
   62 | int func(int a, int b, int c, int d, int dp[19][19][19][19])
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c:77:70: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   77 |             dp[a][b][c][d] += min(func(a, b, c, d - 1, dp[19][19][19][19]), min(func(a, b, c + 1, d, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19])));
      |                                                        ~~~~~~~~~~~~~~^~~~
      |                                                                      |
      |                                                                      int
main.c:62:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
   62 | int func(int a, int b, int c, int d, int dp[19][19][19][19])
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c:77:116: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   77 |             dp[a][b][c][d] += min(func(a, b, c, d - 1, dp[19][19][19][19]), min(func(a, b, c + 1, d, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19])));
      |                                                                                                      ~~~~~~~~~~~~~~^~~~
      |                                                                                                                    |
      |                                                                                                                    int
main.c:62:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
   62 | int func(int a, int b, int c, int d, int dp[19][19][19][19])
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c:77:158: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   77 |             dp[a][b][c][d] += min(func(a, b, c, d - 1, dp[19][19][19][19]), min(func(a, b, c + 1, d, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19])));
      |                                                                                                                                                ~~~~~~~~~~~~~~^~~~
      |                                                                                                                                                              |
      |                                                                                                                                                              int
main.c:62:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
   62 | int func(int a, int b, int c, int d, int dp[19][19][19][19])
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c:81:70: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   81 |             dp[a][b][c][d] += min(func(a, b, c - 1, d, dp[19][19][19][19]), min(func(a, b, c + 1, d, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19])));
      |                                                        ~~~~~~~~~~~~~~^~~~
      |                                                                      |
      |                                                                      int
main.c:62:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
   62 | int func(int a, int b, int c, int d, int dp[19][19][19][19])
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c:81:116: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   81 |             dp[a][b][c][d] += min(func(a, b, c - 1, d, dp[19][19][19][19]), min(func(a, b, c + 1, d, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19])));
      |                                                                                                      ~~~~~~~~~~~~~~^~~~
      |                                                                                                                    |
      |                                                                                                                    int
main.c:62:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
   62 | int func(int a, int b, int c, int d, int dp[19][19][19][19])
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c:81:158: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   81 |             dp[a][b][c][d] += min(func(a, b, c - 1, d, dp[19][19][19][19]), min(func(a, b, c + 1, d, dp[19][19][19][19]), func(a, b, c, d + 1, dp[19][19][19][19])));
      |                                                                                                                                                ~~~~~~~~~~~~~~^~~~
      |                                                                                                                                                              |
      |                                                                                                                                                              int
main.c:62:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
   62 | int func(int a, int b, int c, int d, int dp[19][19][19][19])
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c:85:70: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   85 |             dp[a][b][c][d] += min(func(a, b, c, d + 1, dp[19][19][19][19]), min(func(a, b, c - 1, d, dp[19][19][19][19]), func(a, b, c, d - 1, dp[19][19][19][19])));
      |                                                        ~~~~~~~~~~~~~~^~~~
      |                                                                      |
      |                                                                      int
main.c:62:42: note: expected 'int (*)[19][19][19]' but argument is of type 'int'
   62 | int func(int a, int b, int c, int d, int dp[19][19][19][19])
      |                                      ~~~~^~~~~~~~~~~~~~~~~~
main.c:85:116: error: passing argument 5 of 'func' makes pointer from integer without a cast [-Wint-conversion]
   85 |             dp[a][b][c][d] += min(func(a, b, c, d + 1, dp[19][19][19][19]), min(func(a, b, c - 1, d, dp[19][19][19][19]), func(a, b, c, d - 1, dp[19][19][19][19])));
      |                                                                                                      ~~