poj 2704 Pascal's Travels 记忆化dfs或dp

记忆化dfs

当搜索到一个位置，如果这个位置的下面已经被搜索过了，则直接返回它的值

#include <stdio.h>
#include <string.h>

int n;
__int64 vis[36][36];
char board[36][36];

__int64 dfs(int x,int y)
{
    int i;
    if(x==n-1&&y==n-1)return 1;
    if(board[x][y]=='0')return 0;
    if(vis[x][y])return vis[x][y];
    if(x+board[x][y]-'0'<n)
        vis[x][y]+=dfs(x+board[x][y]-'0',y);
    if(y+board[x][y]-'0'<n)
        vis[x][y]+=dfs(x,y+board[x][y]-'0');
    return vis[x][y];
}

int main()
{
    int i,j;
    while (scanf("%d",&n)!=EOF)
    {
        if(n==-1)break;
        for (i=0;i<n;i++)
            scanf("%s",board[i]);
        memset(vis,0,sizeof(vis));
        printf("%lld\n",dfs(0,0));
    }
    return 0;
}

dp

#include <stdio.h>
#include <string.h>

__int64 vis[50][50];
char board[50][50];

int main()
{
    int i,j,n;
    while (scanf("%d",&n)!=EOF)
    {
        if(n==-1)break;
        for (i=0;i<n;i++)
            scanf("%s",board[i]);
        memset(vis,0,sizeof(vis));
        vis[0][0]=1;
        for (i=0;i<n;i++)
        {
            for (j=0;j<n;j++)
            {
                if(board[i][j]=='0')continue;
                vis[i+board[i][j]-'0'][j]+=vis[i][j];
                vis[i][j+board[i][j]-'0']+=vis[i][j];
            }
        }
        printf("%lld\n",vis[n-1][n-1]);
    }
    return 0;
}