HDU 1312(BFS)

来源：互联网发布：上海行知小学怎么样编辑：程序博客网时间：2024/04/28 08:52

题意：“.”是red方格，“#”是black方格，“@”是起点。求从起点开始走，可以到达的方格（包括起点），red方格不能走，相当于墙壁。

#include <cstdio>#include <queue>#include <algorithm>using namespace std;char map[25][25];bool visit[25][25];int count;const int direction[4][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};struct Node{    int x, y;    Node() {}    Node(int _x, int _y) : x(_x), y(_y) {}    Node next(int i)    {        return Node(x+direction[i][0], y+direction[i][1]);    }    bool visit()    {        return ::visit[x][y];    }    void set()    {        ++::count;        ::visit[x][y] = true;    }    bool legal()    {        return map[x][y] != '#';    }};int main(){    int n, m, i, j, x, y;    memset(map[0], '#', sizeof map[0]);    while (scanf("%d%d", &m, &n) != EOF, n || m)    {        for (i = 1; i <= n; ++i)            scanf("%s", map[i]+1), map[i][0] = map[i][m+1] = '#';        memset(map[n+1], '#', sizeof map[0]);        memset(visit, false, sizeof visit);        for (i = 1; i <= n; ++i)            for (j = 1; j <= m; ++j)                if (map[i][j] == '@')                {                    x = i, y = j;                }        ::count = 0;        queue<Node> q;        q.push(Node(x, y));        Node(x, y).set();        Node p, n;        while (!q.empty())        {            p = q.front();            q.pop();            for (i = 0; i < 4; ++i)            {                n = p.next(i);                if (!n.legal()) continue;                if (n.visit()) continue;                n.set();                q.push(n);            }        }        printf("%d\n", ::count);    }    return 0;}

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