P1434-滑雪

#include <bits/stdc++.h>
using namespace std;
#define _for(i,a,b) for(int i = (a);i < b;i ++)
const int maxn = 110;

int m[maxn][maxn];
int ms[maxn][maxn];
int R,C;
int rnt = 1;
int dx[] = {1,-1,0,0};
int dy[] = {0,0,1,-1};
bool valid(int x,int y)
{
    return x>=0 && y>=0 && x<R && y<C;
}
int msf(int cx,int cy)
{
    if(ms[cx][cy]) return ms[cx][cy];
    ms[cx][cy] = 1;
    _for(i,0,4)
    {
        int nx = cx+dx[i];
        int ny = cy+dy[i];
        
        if(valid(nx,ny) && m[nx][ny] < m[cx][cy])
            ms[cx][cy] = max(ms[cx][cy],msf(nx,ny)+1);
    }
    return ms[cx][cy];
}
int main()
{
    scanf("%d%d",&R,&C);
    memset(m,0,sizeof(m));
    memset(ms,0,sizeof(ms));
    
    _for(i,0,R)
        _for(j,0,C)
            scanf("%d",&m[i][j]);
    
    _for(i,0,R)
        _for(j,0,C)
            rnt = max(rnt,msf(i,j));
    
    printf("%d
",rnt);
    return 0;
}