hdu 1078 FatMouse and Cheese(記憶化搜索)
Problem Description
FatMouse has stored some cheese in a city. The city can be considered as a square grid of dimension n: each grid location is labelled (p,q) where 0 <= p < n and 0 <= q < n. At each grid location Fatmouse has hid between 0 and 100 blocks of cheese in a hole. Now he's going to enjoy his favorite food.
FatMouse begins by standing at location (0,0). He eats up the cheese where he stands and then runs either horizontally or vertically to another location. The problem is that there is a super Cat named Top Killer sitting near his hole, so each time he can run at most k locations to get into the hole before being caught by Top Killer. What is worse -- after eating up the cheese at one location, FatMouse gets fatter. So in order to gain enough energy for his next run, he has to run to a location which have more blocks of cheese than those that were at the current hole.
Given n, k, and the number of blocks of cheese at each grid location, compute the maximum amount of cheese FatMouse can eat before being unable to move.
Input
There are several test cases. Each test case consists of
a line containing two integers between 1 and 100: n and k
n lines, each with n numbers: the first line contains the number of blocks of cheese at locations (0,0) (0,1) ... (0,n-1); the next line contains the number of blocks of cheese at locations (1,0), (1,1), ... (1,n-1), and so on.
The input ends with a pair of -1's.
Output
For each test case output in a line the single integer giving the number of blocks of cheese collected.
Sample Input
3 1 1 2 5 10 11 6 12 12 7 -1 -1
Sample Output
37
Source
Zhejiang University Training Contest 2001
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普通搜索會超時的 感覺這道題和滑雪（poj1088,nyoj10）一樣 只不過多了一些方向
首先附上超時代碼 +理解錯誤（He eats up the cheese where he stands and then runs either horizontally or vertically to another location.）
#include
#include
int n,k;
int map[105][105];
bool vis[105][105];
int dir[4][2]={1,0,-1,0,0,1,0,-1};
int max;
bool limit(int x1,int y1,int x,int y)
{
if(vis[x1][y1]||x1<0||y1<0||x1>=n||y1>=n||map[x1][y1]<=map[x][y])
return false;
return true;
}
void dfs(int x,int y,int sum)
{
if(sum>max)
max=sum;
for(int i=0;in+n)
k=n+n;
for(int i=0;i理解為可以任意走k步了 Wa也是應該的
記憶化搜索：
#include
#include
#include
#include
using namespace std;
int n,k,result;
int map[105][105];
int dp[105][105];
int dir[4][2]={1,0,-1,0,0,1,0,-1};
struct node
{
int x,y;
};
bool limit(int x1,int y1,int x,int y)
{
if(x1<0||y1<0||x1>=n||y1>=n||map[x1][y1]<=map[x][y])
return false;
return true;
}
int dfs(int x,int y)
{
if(dp[x][y])
return dp[x][y];
for(int i=1;i<=k;i++)
{
for(int j=0;j<4;j++)
{
int x1=x+dir[j][0]*i;
int y1=y+dir[j][1]*i;
if(limit(x1,y1,x,y))
{
int z=dfs(x1,y1);
if(dp[x][y]
