给定一个n个点,m条边的无向图,其中你在第i个点建立旅游站点的费用为Ci.在这张图中,任意两点间不存在节点数超过10的简单路径.请找到一种费用最小的建立旅游站点的方案,使得每个点要么建立了旅游站点,要么与它有边直接相连的点里至少有一个点建立了旅游站点. 题解 //minamoto #include<iostream> #include<cstdio> using namespace std; #define getc() (p1==p2&&(p2=(p1=buf)+…

洛谷题面传送门 考虑一个平凡的 DP:我们设 \(dp_i\) 表示前 \(i\) 辆车一来一回所需的最小时间. 注意到我们每次肯定会让某一段连续的火车一趟过去又一趟回来,故转移可以枚举上一段结束位置,设为 \(j\),那么有转移 \[dp_i=\min\limits_{j}\{\max(dp_j+i-j-1,a_i)+2s+i-j-1\} \] 在这里我们不妨假设 \(a_i<a_{i+1}\),这个可以通过从左到右扫一遍并执行 \(a_i\leftarrow\max(a_{i-1}+1,a_…

P3573 [POI2014]RAJ-Rally 题意: 给定一个\(N\)个点\(M\)条边的有向无环图,每条边长度都是\(1\). 请找到一个点,使得删掉这个点后剩余的图中的最长路径最短. 输入输出格式 输入格式: 第一行包含两个正整数\(N\),\(M\),表示点数.边数. 接下来\(M\)行每行包含两个正整数\(A_i,B_i\),表示\(A_i\)到\(B_i\)有一条边. 输出格式: 包含一行两个整数\(x,y\),用一个空格隔开,\(x\)为要删去的点,\(y\)为删除x$后图中的…

P3572 [POI2014]PTA-Little Bird 题目描述 In the Byteotian Line Forest there are nn trees in a row. On top of the first one, there is a little bird who would like to fly over to the top of the last tree. Being in fact very little, the bird might lack the s…

P3576 [POI2014]MRO-Ant colony 题目描述 The ants are scavenging an abandoned ant hill in search of food. The ant hill has nn chambers and n-1n−1 corridors connecting them. We know that each chamber can be reached via a unique path from every other chamber…

P3576 [POI2014]MRO-Ant colony 题目描述 The ants are scavenging an abandoned ant hill in search of food. The ant hill has nn chambers and n-1n−1 corridors connecting them. We know that each chamber can be reached via a unique path from every other chamber…

题目传送门 MRO-Ant colony 题目描述 The ants are scavenging an abandoned ant hill in search of food. The ant hill has nn chambers and n-1n−1 corridors connecting them. We know that each chamber can be reached via a unique path from every other chamber. In othe…

传送门 简单主席树啊. 但听说有随机算法可以秒掉%%%(本蒟蒻并不会) 直接维护值域内所有数的出现次数之和. 当这个值不大于区间总长度的一半时显然不存在合法的数. 这样在主席树上二分查值就行了. 代码: #include<bits/stdc++.h> #define N 500005 using namespace std; inline int read(){ int ans=0; char ch=getchar(); while(!isdigit(ch))ch=getchar(); whi…

题意:给一个数列,每次询问一个区间内有没有一个数出现次数超过一半 题解: 最近比赛太多,都没时间切水题了,刚好日推了道主席树裸题,就写了一下 然后 WA80 WA80 WA0 WA90 WA80 ?????? 结果重新审题发现没有数据范围???? 哦,原来是500000,我是真的菜 因为必须要一个数出现超过一半 所以这个数肯定会在左子树和右子树中总个数和较大的那个里. 显然这样二分找到树底复杂度是logn的 如果此时树底这个点的数值大于一半,那么就输出这个解,否则puts("0") 以…

题目描述 An annual bicycle rally will soon begin in Byteburg. The bikers of Byteburg are natural long distance cyclists. Local representatives of motorcyclists, long feuding the cyclists, have decided to sabotage the event. There are intersections in Byt…