这题一开始的思路应该是直接从源点进行BFS搜索K短路. 但这样的复杂度在点数和K的值增大后将会变得很大. 而A*算法则构造一个h(x),在进行BFS时,每次都抛出最小的h(x)从而使汇点的出队速度加快. 这题则是先进行一次Dijstra求出每个点到汇点的最短路h(x)从而在优先队列中抛出最小的f(x) A*算法就是启发式搜索,基本形式就是这样:f(x)=g(x)+h(x);其中f(x)代表在x点所需要的总代价,而g(x)代表:从源点到x点已经耗费的实际代价,h(x)代表从x到终点需要的估计代价,…

"Good man never makes girls wait or breaks an appointment!" said the mandarin duck father. Softly touching his little ducks' head, he told them a story. "Prince Remmarguts lives in his kingdom UDF – United Delta of Freedom. One day their ne…

第一道第K短路的题目 QAQ 拿裸的DIJKSTRA + 不断扩展的A* 给2000MS过了 题意:大意是 有N个station 要求从s点到t点 的第k短路 (不过我看题意说的好像是从t到s 可能是出题人写错了) 从这题中还真的学到了很多1.第k短路的算法 A* 还有用边表实现dij (注:以下部份资料来源于网上)所谓A*就是启发是搜索 说白了就是给搜索一个顺序使得搜索更加合理减少无谓的搜索. 如何来确定搜索的顺序?..也就是用一个值来表示 这个值为f[n]..每次搜索取f[x]最小的拓展 那…

Remmarguts' Date Time Limit: 4000MS Memory Limit: 65536K Total Submissions: 33081 Accepted: 8993 Description "Good man never makes girls wait or breaks an appointment!" said the mandarin duck father. Softly touching his little ducks' head, he to…

http://poj.org/problem?id=2449 Time Limit: 4000MS   Memory Limit: 65536K Total Submissions: 30754   Accepted: 8394 Description "Good man never makes girls wait or breaks an appointment!" said the mandarin duck father. Softly touching his little…

http://poj.org/problem?id=2449 Remmarguts' Date Time Limit: 4000MS   Memory Limit: 65536K Total Submissions: 18168   Accepted: 4984 Description "Good man never makes girls wait or breaks an appointment!" said the mandarin duck father. Softly tou…

Remmarguts' Date http://poj.org/problem?id=2449 Time Limit: 4000MS   Memory Limit: 65536K Total Submissions: 30772   Accepted: 8397 Description "Good man never makes girls wait or breaks an appointment!" said the mandarin duck father. Softly tou…

http://poj.org/problem?id=2449 不会.. 百度学习.. 恩. k短路不难理解的. 结合了a_star的思想.每动一次进行一次估价,然后找最小的(此时的最短路)然后累计到k 首先我们建反向边,跑一次从汇到源的最短路,将跑出来的最短路作为估价函数h 根据f=g+h 我们将源s先走,此时实际价值g为0,估价为最短路(他们的和就是s-t的最短路) 将所有s所连的边都做相同的处理,加入到堆中(假设此时到达的点为x,那么x的g等于s到这个点的边权,因为根据最优,g+h此时是从x…

题目链接:http://poj.org/problem?id=2449 "Good man never makes girls wait or breaks an appointment!" said the mandarin duck father. Softly touching his little ducks' head, he told them a story. "Prince Remmarguts lives in his kingdom UDF – Unite…

题目链接:http://poj.org/problem?id=2449 Time Limit: 4000MS Memory Limit: 65536K Description "Good man never makes girls wait or breaks an appointment!" said the mandarin duck father. Softly touching his little ducks' head, he told them a story. &quo…