poj 3501 Escape from Enemy Territory(预处理&二分&bfs)

Escape from Enemy Territory Time Limit: 5000MS   Memory Limit: 65536K Total Submissions: 2301   Accepted: 637 Description A small group of commandos has infiltrated deep into enemy territory. They have just accomplished their mission and now have to return to their rendezvous point. Of course they don’t want to get caught even if the mission is already over. Therefore they decide to take the route that will keep them as far away from any enemy base as possible. Being well prepared for the mission, they have a detailed map of the area which marks all (known) enemy bases, their current position and the rendezvous point. For simplicity, we view the the map as a rectangular grid with integer coordinates (x, y) where 0 ≤ x < X, 0 ≤ y< Y. Furthermore, we approximate movements as horizontal and vertical steps on this grid, so we use Manhattan distance: dist((x1, y1), (x2, y2)) = |x2 − x1| + |y2 − y1|. The commandos can only travel in vertical and horizontal directions at each step. Can you help them find the best route? Of course, in case that there are multiple routes that keep the same minimum distance to enemy bases, the commandos want to take a shortest route that does so. Furthermore, they don’t want to take a route off their map as it could take them in unknown, dangerous areas, but you don’t have to worry about unknown enemy bases off the map. Input On the first line one positive number: the number of testcases, at most 100. After that per testcase: One line with three positive numbers N, X, Y. 1 ≤ N ≤ 10 000 is the number of enemy bases and 1 ≤ X, Y ≤ 1 000 the size of the map: coordinates x, y are on the map if 0 ≤ x < X, 0 ≤ y < Y. One line containing two pairs of coordinates xi, yi and xr, yr: the initial position of the commandos and the rendezvous point. N lines each containing one pair of coordinates x, y of an enemy base. All pairs of coordinates are on the map and different from each other. Output Per testcase: One line with two numbers separated by one space: the minimum separation from an enemy base and the length of the route. Sample Input 2 1 2 2 0 0 1 1 0 1 2 5 6 0 0 4 0 2 1 2 3 Sample Output 1 2 2 14 Source Northwestern Europe 2007

题意：

给你一张X*Y矩形地图。上面有些点上有敌营。给你起点和终点要你找出一条最优路径。满足最优路径上的点离敌营的最近最短距离是所有路径最短的。若有多条找路径最短的一条。

思路：

感觉有的dfs的迭代加深。通过二分来确定路径离敌营最短距离。然后bfs来验证。

详细见代码：

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