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CF 1003D Coins and Queries【位运算/硬币值都为2的幂/贪心】

Polycarp has n coins, the value of the i-th coin is ai. It is guaranteed that all the values are integer powers of 2 (i.e. ai=2d for some non-negative...

2018-07-22

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CF 1003C Intense Heat【前缀和/精度/双层暴力枚举】

The heat during the last few days has been really intense. Scientists from all over the Berland study how the temperatures and weather change, and the...

2018-07-21

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CF 1003B Binary String Constructing 【构造/找规律/分类讨论】

You are given three integers a, b and x. Your task is to construct a binary string s of length n=a+b such that there are exactly a zeroes, exactly b o...

2018-07-21

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CF 1005C Summarize to the Power of Two 【hash/STL-map】

A sequence a1,a2,…,an is called good if, for each element ai, there exists an element aj (i≠j) such that ai+aj is a power of two (that is, 2d for some...

2018-07-21

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CF 1005B Delete from the Left 【模拟数组操作/正难则反】

You are given two strings s and t. In a single move, you can choose any of two strings and delete the first (that is, the leftmost) character. After a...

2018-07-21

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CF 1005A Tanya and Stairways 【STL】

Little girl Tanya climbs the stairs inside a multi-storey building. Every time Tanya climbs a stairway, she starts counting steps from 1 to the number...

2018-07-21

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CF 1009A Game Shopping 【双指针/模拟】

Maxim wants to buy some games at the local game shop. There are n games in the shop, the i-th game costs ci. Maxim has a wallet which can be represen...

2018-07-21

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POJ 3264 Balanced Lineup 【线段树/区间最值差】

Balanced Lineup Time Limit: 5000MS Memory Limit: 65536K Total Submissions: 62103 Accepted: 29005 Case Time Limit: 2000MS Description For the daily mi...

2018-07-17

0 367

双向BFS

我们知道，BFS是往广处去搜索，我们把这想象成一个以起点为圆心的一个圆，每向前走一步，就是圆的半径增大一个单位，而圆的每个单位面积上是一种状态，当圆增大到目标点那么大时，找到了答案，搜索结束。那么显然的，当半径较大时，每走一步就会有十分大量的状态需要来储存（ S=πr² ）。通常的，我们用“判重”的...

2018-07-14

0 369

HDU 1043 Eight 【经典八数码输出路径/BFS/A*/康托展开】

本题有写法好几个写法，但主要思路是BFS： No。1 采用双向宽搜，分别从起始态和结束态进行宽搜，暴力判重。如果只进行单向会超时。 No。2 采用hash进行判重，宽搜采用单向就可以AC。 No。3 运用康拓展开进行判重，即使采用单向宽搜时间效率也很高。哈希是想到了，但是我们应该选择什么哈希...

2018-07-14

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