记忆化搜索

p1434 滑雪 　　https://www.luogu.org/problem/P1434

总结：

1.将每个点都搜一遍，用dp数组记录每个点的最大解

 

#include<bits/stdc++.h>
using namespace std;
int dx[4] = {0, 0, 1, -1},
  	dy[4] = {1, -1, 0, 0};
int mapp[105][105], dp[105][105];
int maxx, r, c;

int dfs(int x, int y)
{
	if(dp[x][y] != 0) return dp[x][y];
	int t, maxt = 1;
	for(int i = 0; i < 4; i++)
	{
		int nx = x+dx[i]; int ny = y+dy[i];
		if(nx > 0 && ny > 0 && nx <= r && ny <= c && mapp[nx][ny] > mapp[x][y])
		{
			t = dfs(nx, ny) + 1;
			maxt = max(t, maxt);
		}
	}
	dp[x][y] = maxt;
	return maxt;
}

int main()
{
	memset(dp, 0, sizeof(dp));
	cin >> r >> c;
	for(int i = 1; i <= r; i++)
		for(int j = 1; j <= c; j++)
			cin >> mapp[i][j];
	for(int i = 1; i <= r; i++)
		for(int j = 1; j <= c; j++)
		{
			dp[i][j] = dfs(i, j);
			maxx = max(maxx, dp[i][j]);
		}
	cout << maxx;
	return 0;
}