HDU - 1078（dp+bfs防止Memory Limit ）

Topic Source: http://acm.hdu.edu.cn/showproblem.php?pid=1078

Meaning of the questions: from (1,1) to start you can only walk a straight line, a distance of not more than k, plus the value of the grid went on a grid, ask the greatest value.

The first written bfs found Memory Limit, in order to reduce space on the queue marked prevent multiple re-entry queue to go, you can cancel the mark when the queue.

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<vector>
#include<map>
#include<algorithm>
#include<queue>
#define MAX_len 50100*4
using namespace std;
typedef long long ll;
int a[110][110];
int dp[110][110];
int book[110][110];
struct A {
    int x,y;
};
int main()
{
    int n,k;
    while(scanf("%d %d",&n,&k)!=EOF)
    {
        memset(book,0,sizeof(book));
        queue<A>hh;
        if(n==-1&&k==-1)
            break;
        int i,j;
        for(i=1;i<=n;i++)
        {
            for(j=1;j<=n;j++)
            {
                scanf("%d",&a[i][j]);
            }
        }
        memset(dp,0,sizeof(dp));
        dp[1][1]=a[1][1];
        A head;
        head.x=1;
        head.y=1;
        hh.push(head);
        while(!hh.empty())
        {
            head=hh.front();
    //        printf("%d %d\n",head.x,head.y);
            for(i=1;i<=k;i++)
            {
                int xx=head.x+i;
                int yy=head.y;
                if(xx<1||yy<1||xx>n||yy>n||a[xx][yy]<=a[head.x][head.y])
                {
                    continue;
                }
                dp[xx][yy]=max(dp[xx][yy],dp[head.x][head.y]+a[xx][yy]);
                A tail;
                tail.x=xx;
                tail.y=yy;
                    if(!book[xx][yy])
                {
                hh.push(tail);
                book[xx][yy]=1;
                }
            }
            for(i=1;i<=k;i++)
            {
                int xx=head.x-i;
                int yy=head.y;
                if(xx<1||yy<1||xx>n||yy>n||a[xx][yy]<=a[head.x][head.y])
                {
                    continue;
                }
                dp[xx][yy]=max(dp[xx][yy],dp[head.x][head.y]+a[xx][yy]);
                A tail;
                tail.x=xx;
                tail.y=yy;
                   if(!book[xx][yy])
                {
                hh.push(tail);
                book[xx][yy]=1;
                }

            }
            for(i=1;i<=k;i++)
            {
                int xx=head.x;
                int yy=head.y+i;
                if(xx<1||yy<1||xx>n||yy>n||a[xx][yy]<=a[head.x][head.y])
                {
                    continue;
                }
                dp[xx][yy]=max(dp[xx][yy],dp[head.x][head.y]+a[xx][yy]);
                A tail;
                tail.x=xx;
                tail.y=yy;
                        if(!book[xx][yy])
                {
                hh.push(tail);
                book[xx][yy]=1;
                }

            }
            for(i=1;i<=k;i++)
            {
                int xx=head.x;
                int yy=head.y-i;
                if(xx<1||yy<1||xx>n||yy>n||a[xx][yy]<=a[head.x][head.y])
                {
                    continue;
                }
                dp[xx][yy]=max(dp[xx][yy],dp[head.x][head.y]+a[xx][yy]);
                A tail;
                tail.x=xx;
                tail.y=yy;
                if(!book[xx][yy])
                {
                hh.push(tail);
                book[xx][yy]=1;
                }
            }
            hh.pop();
            book[head.x][head.y]=0;
        }
        int ans=0;
        for(i=1;i<=n;i++)
        {
            for(j=1;j<=n;j++)
            {
                ans=max(ans,dp[i][j]);
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}