uva-10422-骑士-搜索题

题意:

给你一个5X5的图,棋盘上骑士的走法自己去百度,问能不能在10步内走到目标图,

解题思路:

从目标图开始往前走10步,保存所有能走到的图,然后输入,查找是否存在这个图,存在就是可以走到,不存在,走不到

使用map集合保存状态图,优先队列对状态重排序

#include <iostream>
#include <stdio.h>
#include <string>
#include <map>
#include <queue>

using namespace std;

struct Dir
{
        int x, y;
};

struct Node
{
        int x,y;
        string str;
        int step;
        bool operator () (const Node& n1,const Node& n2)const
        {
            return n1.step>n2.step;
        }
};
//使用优先队列对状态重排序
priority_queue<Node, vector<Node>, Node> q;

Dir dir[] =
{
        { +1, -2 },
        { +2, +1 },
        { +2, -1 },
        { -1, +2 },
        { -2, +1 },
        { -2, -1 },
        { -1, -2 },
        { +1, +2 }
};



map<string, int> maps;
const int N=5;

string nextStr(int cr, int cc, int r, int c, string cur)
{
    string str(cur);
    char curc = cur[cr * N + cc];
    char nextc = cur[r * N + c];
    str[cr * N + cc] = nextc;
    str[r * N + c] = curc;
    return str;
}


void bfs()
{
    while(q.empty()==false)
    {
        Node n = q.top();
        q.pop();
        string cur = n.str;
        int depth = n.step;
        int cr = n.x;
        int cc = n.y;
        //已经到10步
        if(depth==10)
            return;
        for(int i = 0; i < 8; i++)
        {
                //nx row
                int r = dir[i].x + cr;
                //col
                int c = dir[i].y + cc;
                if(r < 0 || c < 0 || r >= N || c >= N)
                    continue;
                string str=nextStr(cr, cc, r, c, cur);
                if(maps.find(str)!=maps.end())
                    continue;
                maps[str] = depth+1;
                Node nNode;
                nNode.x=r;
                nNode.y=c;
                nNode.step=depth+1;
                nNode.str=str;
                q.push(nNode);
        }
    }
}

int main()
{
    freopen("d://1.text", "r", stdin);
    //5x5图
    //目标图
    string aim =
            "11111"
            "01111"
            "00 11"
            "00001"
            "00000";
    Node iNode;
    iNode.step=0;
    iNode.str = aim;
    iNode.x = 2;
    iNode.y = 2;
    q.push(iNode);
    maps[aim] = 0;
    bfs();
    int total;
    cin >> total;
    getchar();
    while (total--)
    {
        string str = "";
        string inStr = "";
        for(int i = 0; i < 5; i++)
        {
            getline(cin, inStr);
            str += inStr;
        }
        map<string, int>::iterator s;
        int ok = 0;
        for(s = maps.begin(); s != maps.end(); ++s)
        {
            if(s->first == str)
            {
                ok=1;
                cout<<"Solvable in "<<s->second<<" move(s)."<<endl;
                break;
            }
        }
        if(!ok)
            cout<<"Unsolvable in less than 11 move(s)."<<endl;

    }

    return 0;
}