标签：

Rescue

7 8
#.#####.
#.a#..r.
#..#x...
..#..#.#
#...##..
.#......
........

13

解题思路：

简单的优先队列题目。复习一下优先队列用法.

代码：

#include <iostream>
#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <stdlib.h>
#include <cmath>
#include <iomanip>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <cctype>
using namespace std;
const int maxn=202;
char mp[maxn][maxn];
bool vis[maxn][maxn];
int dx[4]={0,0,-1,1};
int dy[4]={-1,1,0,0};
int sx,sy,ex,ey;
int n,m;

struct Node
{
    int x,y;
    int step;
};
int step[maxn][maxn];

bool operator<(Node a,Node b)
{
    return a.step>b.step;
}

bool ok(int x,int y)
{
    if(x>=1&&x<=n&&y>=1&&y<=m&&mp[x][y]!='#')
        return true;
    return false;
}

void BFS(int x,int y)
{
    step[x][y]=0;
    memset(vis,0,sizeof(vis));
    vis[x][y]=1;
    priority_queue<Node>q;
    Node tp;
    tp.x=x,tp.y=y,tp.step=0;
    q.push(tp);
    while(!q.empty())
    {
        Node first=q.top();
        if(first.x==ex&&first.y==ey)
            break;
        q.pop();
        for(int i=0;i<4;i++)
        {
            int nextx=first.x+dx[i];
            int nexty=first.y+dy[i];
            if(!vis[nextx][nexty]&&ok(nextx,nexty))
            {
                vis[nextx][nexty]=1;
                tp.x=nextx;
                tp.y=nexty;
                if(mp[nextx][nexty]=='x')
                {
                    step[nextx][nexty]=first.step+2;
                    tp.step=first.step+2;
                }
                else
                {
                    step[nextx][nexty]=first.step+1;
                    tp.step=first.step+1;
                }
                q.push(tp);
            }
        }
    }
}

int main()
{
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        for(int i=1;i<=n;i++)
            for(int j=1;j<=m;j++)
        {
            cin>>mp[i][j];
            if(mp[i][j]=='r')
                sx=i,sy=j;
            else if(mp[i][j]=='a')
                ex=i,ey=j;
        }
        BFS(sx,sy);
        if(!vis[ex][ey])
            printf("Poor ANGEL has to stay in the prison all his life.\n");
        else
            printf("%d\n",step[ex][ey]);
    }
    return 0;
}

优先队列用法：

///优先队列是默认int从大到小priority_queue<int>q1，也可以定义为从小到大priority_queue<int,vector<int>,greater<int> >q2;
也可以自定义优先级，重载<

#include <iostream>
#include <functional>
#include <queue>
using namespace std;

///自定义优先级，两种写法,按照优先级从大到小的顺序
/*
struct node
{
    friend bool operator<(node n1,node n2)
    {
        return n1.priority<n2.priority;
    }
    int priority;
    int value;
};*/

struct node
{
    int priority;
    int value;
};
bool operator<(node a,node b)
{
    return a.priority<b.priority;
}


int main()
{
    const int len=5;
    int i;
    int a[len]={3,5,9,6,2};
    //优先队列中从大到小输出
    priority_queue<int>q1;
    for(i=0;i<len;i++)
        q1.push(a[i]);
    for(int i=0;i<len;i++)
    {
        cout<<q1.top();
        q1.pop();
    }
    cout<<endl;
    //优先队列中从小到大输出

    /**
    priority_queue<int,vector<int>,greater<int> >q2;
    for(i=0;i<len;i++)
        q2.push(a[i]);
    for(i=0;i<len;i++)
    {
        cout<<q2.top();
        q2.pop();
    }*/

    priority_queue<int,vector<int>,greater<int> >q;
    for(int i=0;i<len;i++)
        q.push(a[i]);
    while(!q.empty())
    {
        cout<<q.top();
        q.pop();
    }
    cout<<endl;
    //按照某个优先级输出,该代码中为priority值大的先输出
    priority_queue<node>q3;
    node b[len];
    b[0].priority=6;b[0].value=1;
    b[1].priority=9;b[1].value=5;
    b[2].priority=2;b[2].value=3;
    b[3].priority=8;b[3].value=2;
    b[4].priority=1;b[4].value=4;
    for(i=0;i<len;i++)
        q3.push(b[i]);
    cout<<"优先级"<<'\t'<<"值"<<endl;
    for(i=0;i<len;i++)
    {
        cout<<q3.top().priority<<'\t'<<q3.top().value<<endl;
        q3.pop();
    }
    return 0;
}

运行：

96532
23569

优先级  值
9       5
8       2
6       1
2       3
1       4

[ACM] HDU 1242 Rescue (优先队列）

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原文地址：http://blog.csdn.net/sr_19930829/article/details/42706469