题目链接: HDU - 1501 Given three strings, you are to determine whether the third string can be formed by combining the characters in the first two strings. The first two strings can be mixed arbitrarily, but each must stay in its original order.For examp…

题目大意:个字符串.此题是个非常经典的dfs题. 解题思路:DFS 代码如下:有详细的注释 /* * 1501_2.cpp * * Created on: 2013年8月17日 * Author: Administrator */ #include <iostream> using namespace std; char str1[201], str2[201], str3[401]; int len1, len2, len3; bool flag; bool hash[201][201];…

HDU 1501 Zipper [DFS+剪枝] Problem Description Given three strings, you are to determine whether the third string can be formed by combining the characters in the first two strings. The first two strings can be mixed arbitrarily, but each must stay in…

意甲冠军  是否可以由串来推断a,b字符不改变其相对为了获取字符串的组合c 本题有两种解法  DP或者DFS 考虑DP  令d[i][j]表示是否能有a的前i个字符和b的前j个字符组合得到c的前i+j个字符  值为0或者1  那么有d[i][j]=(d[i-1][j]&&a[i]==c[i+j])||(d[i][j-1]&&b[i]==c[i+j])   a,b的下标都是从1開始的  注意0的初始化 #include<cstdio> #include<cs…

Problem Description Given three strings, you are to determine whether the third string can be formed by combining the characters in the first two strings. The first two strings can be mixed arbitrarily, but each must stay in its original order. For e…

链接:http://acm.hdu.edu.cn/showproblem.php?pid=1501 思路:题目要求第三个串由前两个组成,且顺序不能够打乱,搜索大法好 #include<cstdio> #include<iostream> #include<algorithm> #include<math.h> #include<string.h> #include<vector> #include<queue> #incl…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=1072 思路:深搜每一个节点,并且进行剪枝,记录每一步上一次的s1,s2:如果之前走过的时间小于这一次, 就说明有更短的:路径,所以就不用继续遍历下去. #include<iostream> #include<cstdio> #include<cstring> using namespace std; ][],step[][],tim[][],m,n,ans; ][]={{-…

<题目链接> 题目大意:在一个棋盘上给定一个起点和终点,判断这两点是否能通过连线连起来,规定这个连线不能穿过其它的棋子,并且连线转弯不能超过2次. 解题分析:就是DFS从起点开始搜索,只不过搜索的时候需要记录当前的方向和已经转弯的次数,然后通过题目给定的限制条件进行搜索,判断是否存在从起点到终点转弯次数不超过2次的连线.同时,在转弯次数达到两次的时候,我们可以对搜索树进行可行性剪枝,直接判断转弯两次后,该点与终点是否在同一条直线上,从而减少搜索时间. #include <bits/std…

Collect More Jewels Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 6739    Accepted Submission(s): 1564 Problem Description It is written in the Book of The Lady: After the Creation, the cruel…

Zipper Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 4884    Accepted Submission(s): 1742 Problem Description Given three strings, you are to determine whether the third string can be formed…

题目大意:输入有一个T,表示有T组测试数据,然后输入三个字符串,问第三个字符串能否由第一个和第二个字符串拼接而来,拼接的规则是第一个和第二个字符串在新的字符串中的前后的相对的顺序不能改变,问第三个字符串能否由前两个得到. 解题报告:这题用dfs,反过来,将第三个字符串按照从前到后的顺序,看能否拆成第一个和第二个字符串,不过这题如果只是这样搜索的话,很明显会超时,所以要减掉其中一些重复的其情况,定义一个二维数组hash[i][j],初始化都为0,然后如果将hash[i][j]标记为1表示第一个字符…

Sticks Problem Description George took sticks of the same length and cut them randomly until all parts became at most 50 units long. Now he wants to return sticks to the original state, but he forgot how many sticks he had originally and how long the…

题意: 给三个字符串str1.str2.str3 问str1和str2能否拼接成str3.(拼接的意思可以互相穿插) 能输出YES否则输出NO. 思路: 如果str3是由str1和str2拼接而成,str1的前i个字符和str2的前j个字符一定构成str3的前i+j个字符.(因为拼接必须保证字符的顺序不变) 所以,,,这算是个变形的最长公共子序列? DP方程:dp[i][j]:str3的前i+j个字符能否由str1的前i个字符和str2的前j个字符拼接而成.布尔型. 看代码,, 代码: char…

HDOJ 1501 Zipper [DP][DFS+剪枝] Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 10886 Accepted Submission(s): 3925 Problem Description Given three strings, you are to determine whether the third str…

Counting Cliques Time Limit: 8000/4000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 539    Accepted Submission(s): 204 Problem Description A clique is a complete graph, in which there is an edge between every pair…

Equation Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 92    Accepted Submission(s): 24 Problem Description Little Ruins is a studious boy, recently he learned addition operation! He was rewa…

Sum It Up Time Limit : 2000/1000ms (Java/Other)   Memory Limit : 65536/32768K (Java/Other) Total Submission(s) : 4   Accepted Submission(s) : 1 Font: Times New Roman | Verdana | Georgia Font Size: ← → Problem Description Given a specified total t and…

题目链接:http://acm.split.hdu.edu.cn/showproblem.php?pid=5887 题解:这题一看像是背包但是显然背包容量太大了所以可以考虑用dfs+剪枝,贪心得到的不一定是正确答案.当然这题还可以用背包来写,其实这就用到了dp的一些优化就是存状态,递推过程中有些状态是多余的没必要计算这样就可以大大减少空间的利用和时间的浪费 第一份是dfs+剪枝的写法第二份是背包+map存状态的写法. #include <iostream> #include <cstri…

求最久时间即在无环有向图里求最远路径 dfs+剪枝优化 从0节点(自己添加的)出发,0到1~n个节点之间的距离为1.mt[i]表示从0点到第i个节点眼下所得的最长路径 #include<iostream> #include<cstdio> #include<cstring> #include<string> #include<algorithm> #include<vector> using namespace std; const…

Sticks Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 9779    Accepted Submission(s): 2907 Problem Description George took sticks of the same length and cut them randomly until all parts became…

POJ3009 DFS+剪枝 原题: Curling 2.0 Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 16280 Accepted: 6725 Description On Planet MM-21, after their Olympic games this year, curling is getting popular. But the rules are somewhat different from our…

ROADS Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 10777   Accepted: 3961 Description N cities named with numbers 1 ... N are connected with one-way roads. Each road has two parameters associated with it : the road length and the toll…

题目传送门 /* 题意:若干小木棍,是由多条相同长度的长木棍分割而成,问最小的原来长木棍的长度: DFS剪枝:剪枝搜索的好题!TLE好几次,终于剪枝完全! 剪枝主要在4和5:4 相同长度的木棍不再搜索:5 若新的搜索连第一条都没组合出来,直接break: 详细解释:http://blog.csdn.net/lyy289065406/article/details/6647960 http://www.cnblogs.com/devil-91/archive/2012/08/03/2621787.…

题目传送门 /* 题意:告诉一个区间[L,R],问根节点的n是多少 DFS+剪枝:父亲节点有四种情况:[l, r + len],[l, r + len - 1],[l - len, r],[l - len -1,r]; */ #include <cstdio> #include <algorithm> #include <cstring> #include <cmath> #include <queue> using namespace std;…

题目链接 Solution DFS+剪枝 对于一个走过点k,如果有必要再走一次,那么一定是走过k后在k点的最大弹药数增加了.否则一定没有必要再走. 记录经过每个点的最大弹药数,对dfs进行剪枝. #include <iostream> #include <cstring> #include <algorithm> #include <cstdio> #include <map> using namespace std; map<string…

Sticks Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 127771   Accepted: 29926 Description George took sticks of the same length and cut them randomly until all parts became at most 50 units long. Now he wants to return sticks to the or…

HDU.5692 Snacks ( DFS序 线段树维护最大值 ) 题意分析 给出一颗树,节点标号为0-n,每个节点有一定权值,并且规定0号为根节点.有两种操作:操作一为询问,给出一个节点x,求从0号节点开始到x节点,所能经过的路径的权值最大为多少:操作二为修改,给出一个节点x和值val,将x的权值改为val. 可以看出是树上修改问题.考虑的解题方式有DFS序+线段树,树链剖分,CXTree.由于后两种目前还不会,选择用DFS序来解决. 首先对树求DFS序,在求解过程当中,顺便求解树上前缀和(p…

题目大意:原题链接 给定n个节点,任意两个节点之间有权值,把这n个节点分成A,B两个集合,使得A集合中的每一节点与B集合中的每一节点两两结合(即有|A|*|B|种结合方式)权值之和最大. 标记:A集合:true  B集合:false 解法一:dfs+剪枝 #include<iostream> #include<cstring> using namespace std; int n,ans; ]; ][]; void dfs(int i,int cursum) { in[i]=tru…

HDOJ 1501 Zipper [简单DP] Problem Description Given three strings, you are to determine whether the third string can be formed by combining the characters in the first two strings. The first two strings can be mixed arbitrarily, but each must stay in i…

题意:给出n根小棒的长度stick[i],已知这n根小棒原本由若干根长度相同的长木棒(原棒)分解而来.求出原棒的最小可能长度. 思路:dfs+剪枝.蛮经典的题目,重点在于dfs剪枝的设计.先说先具体的实现:求出总长度sum和小棒最长的长度max,则原棒可能的长度必在max~sum之间,然后从小到大枚举max~sum之间能被sum整除的长度len,用dfs求出所有的小棒能否拼凑成这个长度,如果可以,第一个len就是答案. 下面就是关键的了,就是这道题dfs的实现和剪枝的设计: 1.以一个小棒为开头…