hdu1242 Rescue--BFS

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原题链接： http://acm.hdu.edu.cn/showproblem.php?pid=1242

一：题意

x代表卫兵，a代表终点，r代表起始点，.代表路，#代表墙
路花费一秒，x花费两秒
问到达终点的最少时间
思路：BFS+优先队列

二：AC代码

#define _CRT_SECURE_NO_DEPRECATE #define _CRT_SECURE_Cy1_OVERLOAD_STANDARD_NAMES 1 #include<iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <queue>using namespace std;struct Node{int x, y;int step;bool operator<(const Node & node) const{return node.step < step;}};char ch[205][205];int dis[205][205];int dir[4][2] = { 1,0,-1,0,0,1,0,-1 };int sx, sy;//起点，也就是朋友的位置int dx, dy;int n, m;bool bfs(){Node t, tt;priority_queue<Node> pq;t.x = sx;t.y = sy;t.step = 0;pq.push(t);dis[sx][sy] = 0;while (!pq.empty()){t = pq.top();pq.pop();if (t.x == dx&&t.y == dy){printf("%d\n", t.step);return true;}for (int i = 0; i < 4; i++){tt = t;tt.x += dir[i][0];tt.y += dir[i][1];if (tt.x < 0 || tt.y < 0 || tt.x >= n || tt.y >= m || ch[tt.x][tt.y] == '#')continue;tt.step++;if (ch[tt.x][tt.y] == 'x')tt.step++;if (dis[tt.x][tt.y] >= tt.step){dis[tt.x][tt.y] = tt.step;pq.push(tt);}}}return false;}int main() {while (~scanf("%d%d", &n, &m)){for (int i = 0; i < n; i++){getchar();for (int j = 0; j < m; j++){dis[i][j] = 99999999;scanf("%c", &ch[i][j]);if (ch[i][j] == 'a'){dx = i;dy = j;}else if (ch[i][j] == 'r'){sx = i;sy = j;}}}if (!bfs())printf("Poor ANGEL has to stay in the prison all his life.\n");}return 0;}

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