这题转化一下题意就是给一堆形如$a_i + a_j \ne c\quad (a_i\in [0,1],c\in [0,2])$的限制,问从开头开始最多到哪条限制全是有解的. 那么,首先有可二分性,所以直接二分枚举最大处,然后把这些限制加边做一次2-sat就好了.连边的话注意一下细节就行,$c=0$时候就是选$0$必须另一个选$1$,$c=1$是选同类,$c=2$就是选$1$另一个必须选$0$,然后注意一下$i=j$也就是对同一变量的特殊讨论,就是直接赋值型的连边.然后就没了. #include<…

题面描述 Ratish is a young man who always dreams of being a hero. One day his friend Luffy was caught by Pirate Arlong. Ratish set off at once to Arlong's island. When he got there, he found the secret place where his friend was kept, but he could not go…

今天看到讲2-SAT比较好的blog,感觉微微的理解了2-SAT 传送门 参考: https://blog.csdn.net/leolin_/article/details/6680144 题意:你有2*n把钥匙,但是在每一对钥匙中,用了a,就不能用b.你要用这么多钥匙去开尽可能多的门.开门的规则是:每个门对于两把钥匙,用一把去开就ok. 注意2的10次方一点都不大~~1000. 思路:注意开门是有顺序的,所以可以二分答案,每次用mid值规定的门数去建一个图,跑一边tarjan缩点,再check…

题目 Ratish is a young man who always dreams of being a hero. One day his friend Luffy was caught by Pirate Arlong. Ratish set off at once to Arlong's island. When he got there, he found the secret place where his friend was kept, but he could not go s…

题目链接 给n个钥匙对, 每个钥匙对里有两个钥匙, 并且只能选择一个. 有m扇门, 每个门上有两个锁, 只要打开其中一个就可以通往下一扇门. 问你最多可以打开多少个门. 对于每个钥匙对, 如果选择了其中一个钥匙, 那么另一个就不能选. 所以加边(a, b'), (b, a'). 对于每个门, 如果不打开其中一个锁, 那么另一个锁就一定要打开. 所以加边(a', b), (b', a). 然后二分判断就可以了. #include <iostream> #include <vector>…

题目大意:有N串钥匙,M对锁.每串钥匙仅仅能选择当中一把.怎样选择,才干使开的锁达到最大(锁仅仅能按顺序一对一对开.仅仅要开了当中一个锁就可以) 解题思路:这题跟HDU - 3715 Go Deeper 这题的限制比較简单.都是二选一,2-SAT的裸题,仅仅只是加了二分而已 附上HDU - 3715 Go Deeper题解 #include <cstdio> #include <cstring> #include <algorithm> #include <vec…

典型的2-sat问题,题意:有m个门,每个门上俩把锁,开启其中一把即可,现在给n对钥匙(所有 钥匙编号0123456...2n-1),每对钥匙只能用一把,要求尽可能开门多(按顺序,前max个). 关键是题意的分析与转化,只能选一?必然2-sat,每给一对门上的锁对应钥匙的编号,说:必需要这 俩把钥匙的一把(至少),即:a^b,所以,建图了可以,总结通法:对应的数据编号:0123..,每个 数代表原来的一个"状态"/"命题"/"数据",使之01为一…

Get Luffy Out Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 8851   Accepted: 3441 Description Ratish is a young man who always dreams of being a hero. One day his friend Luffy was caught by Pirate Arlong. Ratish set off at once to Arlo…

Language: Default Get Luffy Out Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 7969   Accepted: 3061 Description Ratish is a young man who always dreams of being a hero. One day his friend Luffy was caught by Pirate Arlong. Ratish set o…

Get Luffy Out 题目链接 Ratish is a young man who always dreams of being a hero. One day his friend Luffy was caught by Pirate Arlong. Ratish set off at once to Arlong's island. When he got there, he found the secret place where his friend was kept, but h…