POJ 3009

来源：互联网发布：scala编程思想下载编辑：程序博客网时间：2024/05/22 10:57

题意：模拟一个打冰壶游戏，给出一个地图，每一个点有4种情况。1：冰壶的起点 2：冰壶的终点，冰壶移动到这里游戏成功，退出 3：无障碍的点 4：障碍。

冰壶如果没有撞击到障碍就会一直运动直到越界（游戏失败）或者撞到墙（把墙撞坏）。每次冰壶静止时可以从4个方向敲击冰壶（除非冰壶前方是障碍），要判断能否成功退出游戏，若能，求出敲击的最小次数。另外，如果敲击超过10次，也算游戏失败（这个条件给dfs剪枝用的）

模拟+深搜，模拟过程无限复杂。。。一开始判断方向时总是打错字母，后来回溯时又忘记还原，再后来计数方式又出问题，WA了无数发。做了一个下午才勉强AC。唉，都是泪。

#include<iostream>#include<cstdio>#include<cmath>#include<algorithm>#include<cstring>#include<string>#include<queue>#include<strstream>#define INF 2100000000#define MAXN 1100using namespace std;int map[MAXN][MAXN];int m, n;//bool vis[MAXN*MAXN];int ans;inline bool islegal(const int r, const int c, const int dir){    bool ok = 0;    //right    if(dir == 0)    {        for(int i = c+1; i < m; i++)        {            if(map[r][i] == 1 && i == c+1) break;            if(map[r][i] == 1 || map[r][i] == 3) ok = 1;        }    }    //down    if(dir == 1)    {        for(int i = r+1; i < n; i++)        {            if(map[i][c] == 1 && i == r+1) break;            if(map[i][c] == 1 || map[i][c] == 3) ok = 1;        }    }    //left    if(dir == 2)    {        for(int i = c-1; i >= 0; i--)        {            if(map[r][i] == 1 && i == c-1) break;            if(map[r][i] == 1 || map[r][i] == 3) ok = 1;        }    }    //up    if(dir == 3)    {        for(int i = r-1; i >= 0; i--)        {            if(map[i][c] == 1 && i == r-1) break;            if(map[i][c] == 1 || map[i][c] == 3) ok = 1;        }    }    return ok;}int move(int r, int c, int dir, int& recordmove){    if(dir == 0)    {        for(int i = c+1; i < m; i++)        if(map[r][i] == 1 || map[r][i] == 3)        {            if(map[r][i] == 1)            {                map[r][i] = 0;                recordmove = r*m+i;            }            if(map[r][i] == 3) return r*m+i;            return r*m+i-1;        }    }    else if(dir == 1)    {        for(int i = r+1; i < n; i++)        if(map[i][c] == 1 || map[i][c] == 3)        {            if(map[i][c] == 1)            {                map[i][c] = 0;                recordmove = i*m+c;            }            if(map[i][c] == 3) return i*m+c;            return (i-1)*m+c;        }    }    else if(dir == 2)    {        for(int i = c-1; i >= 0; i--)        if(map[r][i] == 1 || map[r][i] == 3)        {            if(map[r][i] == 1)            {                map[r][i] = 0;                recordmove = r*m+i;            }            if(map[r][i] == 3) return r*m+i;            return r*m+i+1;        }    }    else if(dir == 3)    {        for(int i = r-1; i >= 0; i--)        if(map[i][c] == 1 || map[i][c] == 3)        {            if(map[i][c] == 1)            {                map[i][c] = 0;                recordmove = i*m+c;            }            if(map[i][c] == 3) return i*m+c;            return (i+1)*m+c;        }    }    return -1;}void dfs(int s, int e, int recordmove, int counter){    //if(!ok) return;    if(s == e)    {        ans = min(ans, counter);        return;    }    if(counter >= 10)    {        return;    }    int r = s/m;    int c = s%m;    for(int i = 0; i < 4; i++)    {        if(islegal(r, c, i))        {            recordmove = -1;            int temp = move(r, c, i, recordmove);            //cout << "record x: " << recordmove/m << " y: " << recordmove%m << endl;            dfs(temp, e, -1, counter+1);            if(recordmove != -1)            map[recordmove/m][recordmove%m] = 1;        }    }}int main(){    //freopen("C:/Users/Admin/Desktop/in.txt", "r", stdin);    while(cin >> m >> n && m && n)    {        //memset(vis, 0, sizeof(vis));        int start, end;        for(int i = 0; i < n; i++)        for(int j = 0; j < m; j++)        {            cin >> map[i][j];            if(map[i][j] == 2){ start = i*m+j; map[i][j] = 0; }            else if(map[i][j] == 3) end = i*m+j;        }        ans = INF;        //vis[start] = 1;        dfs(start, end, -1, 0);        if(ans != INF && ans <= 10)        cout << ans << endl;        else        cout << -1 << endl;    }    return 0;}

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