C :

/*
ID: Sfiction
OJ: RQNOJ
PROB: 314
*/
#include <stdio.h>
#define max(a,b) a>b?a:b
#define min(a,b) a<b?a:b
int main()
{
    int map[11][11]={0},f[11][11]={0};
    int i,j,k,N,t;
    scanf("%d",&N);
    while (scanf("%d%d%d",&i,&j,&k)&&(i||j||k)) map[i][j]=k;
    for (i=2;i<=2*N;i++)
        for (t=min(i,N),j=t;j>0;j--)
            for (k=t;k>0;k--)
            {
                f[j][k]=max(f[j][k],f[j-1][k-1]);
                f[j][k]=max(f[j][k],f[j][k-1]);
                f[j][k]=max(f[j][k],f[j-1][k]);
                if (j==k) f[j][k]+=map[j][i-j];
                else f[j][k]+=map[j][i-j]+map[k][i-k];
            }
    printf("%d",f[N][N]);
    return 0;
}

C++ :

#include<cstdio>  
#include<cstring>  
#include<algorithm>  
using namespace std;  
  
int a[11][11];  
int dp[21][11][11];  
const int INF = 999999999;  
  
int operDp(int n)  
{  
    int i, j, k;  
    memset(dp,0,sizeof(dp));  
    for(k = 1; k <= 2 * n; k++)  
    for(i = 1; i <= k; i++)  
    for(j = 1; j <= k; j++)  
    {  
        int tmp = -INF;  
        tmp = max(tmp, dp[k-1][i-1][j-1]);  
        tmp = max(tmp, dp[k-1][i-1][j]);  
        tmp = max(tmp, dp[k-1][i][j-1]);  
        tmp = max(tmp, dp[k-1][i][j]);  
        if(i == j) dp[k][i][j] = tmp + a[k-i+1][i];  
        else dp[k][i][j] = tmp + a[k-i+1][i] + a[k-j+1][j];  
    }  
    return dp[2*n][n][n];  
}  
  
int main()  
{  
    int n, r, c, v;  
    while(scanf("%d",&n) != EOF)  
    {  
        memset(a,0,sizeof(a));  
        while(true)  
        {  
            scanf("%d%d%d",&r,&c,&v);  
            if(!r && !c && !v) break;  
            a[r][c] = v;  
        }  
        printf("%d\n",operDp(n));  
    }  
    return 0;  
}  

Pascal :

uses math;
var
   n,x,y,s,i,j,k,l,maxs:longint;
   p:array[0..10,0..10,0..10,0..10]of longint;
   a:array[0..100,0..100]of longint;
begin
 readln(n);
 readln(x,y,s);
 fillchar(a,sizeof(a),0);
 while (x>0)or(x>0)or(s>0)do
  begin
   a[x,y]:=s;
   readln(x,y,s);
  end;
 fillchar(p,sizeof(p),0);
 for i:=1 to n do
  for j:=1 to n do
   for k:=1 to n do
    for l:=1 to n do
     begin
      p[i,j,k,l]:=max(p[i,j-1,k,l-1],p[i-1,j,k,l-1]);
      maxs:=max(p[i,j-1,k-1,l],p[i-1,j,k-1,l]);
      if maxs>p[i,j,k,l]then p[i,j,k,l]:=maxs;
      if (i=k)and(j=l)then inc(p[i,j,k,l],a[i,j])
      else p[i,j,k,l]:=p[i,j,k,l]+a[i,j]+a[k,l];
     end;
 writeln(p[n,n,n,n]);
end.