题目链接 给n个城市, m条边, q个询问, 每个询问, 输出城市a和b的最短距离, 如果不联通, 输出not connected. 用并查集判联通, 如果不连通, 那么两个联通块之间加一条权值很大的边. 然后树链剖分..... #include <iostream> #include <vector> #include <cstdio> #include <cstring> #include <algorithm> #include <c…

Connections between cities Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 4425    Accepted Submission(s): 1263 Problem Description After World War X, a lot of cities have been seriously damag…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=2874 题意是给你n个点,m条边(无向),q个询问.接下来m行,每行两个点一个边权,而且这个图不能有环路.然后接下来q行,每行给你两个点,问你这两个点的最短距离是多少,要是不相连,则输出一串英文. 首先想到的是用(二分)倍增LCA,但是这题的坑点是两个点可能不在同一个图中,所以我dfs的时候用block[i]标记这个点属于哪一个图中,要是这个点在同一个图中,答案就是cost[u] + cost[v]…

Connections between cities [题目链接]Connections between cities [题目类型]LCA Tarjan &题意: 输入一个森林,总节点不超过N(N<10000),由C次询问(C<1000000),每次询问两个点,如果来联通输出,两点之间的距离,如果不来联通,输出"Not connected" &题解: md,就没人吐槽这题询问时有相等的情况吗?我被这个坑了一天= = 最后把ans数组置为-1才过的,以前一直初…

题意: 给出n个点m条边的图,c次询问 求询问中两个点间的最短距离. 解析: Floyd会T,所以用到了最短路树..具体思想为: 设k为u和v的最近公共祖先 d[i] 为祖结点到i的最短距离  则dis[u][v] = d[u] + d[v] - 2*d[k] 用tarjan的lca求即可 把这题代码当作模板就好啦 #include <iostream> #include <cstdio> #include <sstream> #include <cstring&…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=4822 Problem Description Three countries, Red, Yellow, and Blue are in war. The map of battlefield is a tree, which means that there are N nodes and (N – 1) edges that connect all the nodes. Each country…

题目意思很明白: 给你一棵有n个节点的树,对树有下列操作: I c1 c2 k 意思是把从c1节点到c2节点路径上的点权值加上k D c1 c2 k 意思是把从c1节点到c2节点路径上的点权值减去k Q a 查询节点a的权值 数据大小 节点个数 n[1,50000], 操作次数 op[0,30000]; 不会树链剖分 故只有想其他的方法. 这道题有点类似今年上海网络赛的1003 ,不过那题我没做: 算法思路: 以节点1 为根,求出节点i 的 dfs序列 tim[i][2]; 其中tim[i][0…

Problem Description After World War X, a lot of cities have been seriously damaged, and we need to rebuild those cities. However, some materials needed can only be produced in certain places. So we need to transport these materials from city to city.…

题目链接: Connections between cities Time Limit: 10000/5000 MS (Java/Others)     Memory Limit: 32768/32768 K (Java/Others) Problem Description   After World War X, a lot of cities have been seriously damaged, and we need to rebuild those cities. However,…

Dylans loves tree view code#pragma comment(linker, "/STACK:1024000000,1024000000") #include <iostream> #include <algorithm> #include <cstdio> #include <cstring> #include <vector> #include <queue> #include <…