POJ_1088_dfs

#include<iostream>
#include<cstdio>
using namespace std;
int r,c,a[105][105],maxlen[105][105] = {0};
int dir[4][2] = {-1,0,0,-1,1,0,0,1};
int dfs(int x,int y)
{
    int maxx = 1,len;
    for(int i = 0;i < 4;i++)
    {
        int xx = x+dir[i][0],yy = y+dir[i][1];
        if(xx < 1 || xx > r || yy < 1 || yy > c)    continue;
        if(a[x][y] > a[xx][yy])
        {
            if(maxlen[xx][yy])  len = maxlen[xx][yy]+1;
            else    len = dfs(xx,yy)+1;
            maxx = max(maxx,len);
        }
    }
    maxlen[x][y] = maxx;
    return maxx;
}
int main()
{
    cin >> r >> c;
    for(int i = 1;i <= r;i++)
    {
        for(int j = 1;j <= c;j++)   cin >> a[i][j];
    }
    int ans = 1,len;
    for(int i = 1;i <= r;i++)
    {
        for(int j = 1;j <= c;j++)
        {
            if(maxlen[i][j] == 0)
            {
                len = dfs(i,j);
                ans = max(ans,len);
            }
        }
    }
    cout << ans << endl;
    return 0;
}