POJ 1088-滑雪

矩阵里的数字代表当前点的高度，只能从高的点滑到低的点，求最长能滑的距离。初始点

不规定。我们可以向每个点的四周搜索，能走则就在当前距离加1。并将已经求的值保存在

二维数组中。（记忆化搜索）

 

/*Accepted    252K    47MS    C++    1158B    2012-07-23 16:13:17*/
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;const int MAXN = 105;
const int dx[] = {0, 0, 1, -1};
const int dy[] = {1, -1, 0, 0};int map[MAXN][MAXN], d[MAXN][MAXN];
int R, C, ans;void init()
{int i, j;for( i = 1; i <= R; i ++)for( j = 1; j <= C; j ++){scanf( "%d", &map[i][j]);d[i][j] = -1;}
}
int dfs( int x, int y)
{int i, ans, nx, ny;if( d[x][y] > 0) return d[x][y];ans = 0;for( i = 0; i < 4; i ++){nx = x + dx[i];ny = y + dy[i];if( map[x][y] <= map[nx][ny] || nx < 1 || nx > R || ny < 1 || ny > C)continue;ans = max( ans, dfs(nx, ny) + 1);}return ans;
}int main()
{int i, j;while( scanf( "%d%d", &R, &C) == 2){init();ans = 0;for( i = 1; i <= R; i ++)for( j = 1; j <= C; j ++){d[i][j] = dfs(i, j);ans = max( ans, d[i][j]);}printf( "%d\n", ans + 1);}return 0;
}

 

 下面的代码TLE了

#include<cstdio>
#include<cstring>
#include<cstdlib>
#define MAXN 105
int R, C, lgst;
int map[MAXN][MAXN];
const int dx[] = { 1, -1, 0, 0};
const int dy[] = { 0, 0, 1, -1};

void dfs( int x, int y, int dep)
{
if( x < 0 || x >= R || y < 0 || y >= C) return;
if( lgst < dep) lgst = dep;
for( int d = 0; d < 4; d ++)
    {
int nx = x + dx[d];
int ny = y + dy[d];
if( map[x][y] > map[nx][ny])
            dfs( nx, ny, dep + 1);
    }
}

void init()
{
for( int i = 0; i < R; i ++)
for( int j = 0; j < C; j ++)
        {
            scanf( "%d", &map[i][j]);
        }
}

int main()
{
    scanf( "%d%d", &R, &C);
    init();
    lgst = 1;
for( int i = 0; i < R; i ++)
for( int j = 0; j < C; j ++)
            dfs( i, j, 1);
    printf( "%d\n", lgst);
return 0;
}