题意 : 给出 P 个顶点以及 Q 条有向边,求第一个点到其他各点距离之和+其他各点到第一个点的距离之和的最小值 分析 : 不难看出 min( 第一个点到其他各点距离之和+其他各点到第一个点的距离之和 ) = min( 第一个点到其他各点距离之和) + min( 其他各点到第一个点的距离之和 ),前者较为简单,建好图后直接跑一遍最短路即得,关键在于后者怎么方便的求出来.这里利用到了一个逆向思维,如果将所有的有向边反过来,那么就能求出其他点到源点的最短路了,那么只要存储两种边,一个正向边(即题目所…

Invitation Cards Time Limit: 8000MS   Memory Limit: 262144K Total Submissions: 16178   Accepted: 5262 Description In the age of television, not many people attend theater performances. Antique Comedians of Malidinesia are aware of this fact. They wan…

<题目链接> 题目大意: 有向图,求从起点1到每个点的最短路然后再回到起点1的最短路之和. 解题分析: 在求每个点到1点的最短路径时,如果仅仅只是遍历每个点,对它们每一个都进行一次最短路算法,那么即使是用了堆优化的dijkstra,时间复杂度也高达$O(n^2log(n))$,而本题有1000000个点,毫无疑问,这种想法必然是不可行的,所以我们可以采用逆向思维,将图中的每一条有向边全部反向,然后以1为起点,仅做一次dijkstra,就能得到1到所有点的最短距离,即反向前的,所有点到1点的最短…

POJ 1511 Invitation Cards / UVA 721 Invitation Cards / SPOJ Invitation / UVAlive Invitation Cards / SCU 1132 Invitation Cards / ZOJ 2008 Invitation Cards / HDU 1535 (图论,最短路径) Description In the age of television, not many people attend theater perfor…

Invitation Cards Time Limit: 8000MS   Memory Limit: 262144K Total Submissions: 33435   Accepted: 11104 Description In the age of television, not many people attend theater performances. Antique Comedians of Malidinesia are aware of this fact. They wa…

In the age of television, not many people attend theater performances. Antique Comedians of Malidinesia are aware of this fact. They want to propagate theater and, most of all, Antique Comedies. They have printed invitation cards with all the necessa…

Description In the age of television, not many people attend theater performances. Antique Comedians of Malidinesia are aware of this fact. They want to propagate theater and, most of all, Antique Comedies. They have printed invitation cards with all…

Invitation Cards Time Limit: 8000MS   Memory Limit: 262144K Total Submissions: 18198   Accepted: 5969 Description In the age of television, not many people attend theater performances. Antique Comedians of Malidinesia are aware of this fact. They wan…

Invitation Cards Time Limit: 8000MS Memory Limit: 262144K Total Submissions: 24460 Accepted: 8091 Description In the age of television, not many people attend theater performances. Antique Comedians of Malidinesia are aware of this fact. They want to…

原题: Invitation Cards Time Limit: 8000MS   Memory Limit: 262144K Total Submissions: 31230   Accepted: 10366 Description In the age of television, not many people attend theater performances. Antique Comedians of Malidinesia are aware of this fact. The…