标签归档:DFS

[codeforces 740D] Alyona and a tree

Description

Alyona has a tree with n vertices. The root of the tree is the vertex 1. In each vertex Alyona wrote an positive integer, in the vertex i she wrote ai. Moreover, the girl wrote a positive integer to every edge of the tree (possibly, different integers on different edges).

Let's define dist(v, u) as the sum of the integers written on the edges of the simple path from v to u.

The vertex v controls the vertex u (v ≠ u) if and only if u is in the subtree of v and dist(v, u) ≤ au.

Alyona wants to settle in some vertex. In order to do this, she wants to know for each vertex v what is the number of vertices u such that vcontrols u.

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Codeforces Round#369 Div.2

A. Bus to Udayland

ZS the Coder and Chris the Baboon are travelling to Udayland! To get there, they have to get on the special IOI bus. The IOI bus has nrows of seats. There are 4 seats in each row, and the seats are separated into pairs by a walkway. When ZS and Chris came, some places in the bus was already occupied.

ZS and Chris are good friends. They insist to get a pair of neighbouring empty seats. Two seats are considered neighbouring if they are in the same row and in the same pair. Given the configuration of the bus, can you help ZS and Chris determine where they should sit?

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[bzoj 1024][SCOI2009] 生日快乐

Description

  windy的生日到了,为了庆祝生日,他的朋友们帮他买了一个边长分别为 X 和 Y 的矩形蛋糕。现在包括windy,一共有 N 个人来分这块大蛋糕,要求每个人必须获得相同面积的蛋糕。windy主刀,每一切只能平行于一块蛋糕的一边(任意一边),并且必须把这块蛋糕切成两块。这样,要切成 N 块蛋糕,windy必须切 N-1 次。为了使得每块蛋糕看起来漂亮,我们要求 N块蛋糕的长边与短边的比值的最大值最小。你能帮助windy求出这个比值么?

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[bzoj 1053][HAOI2007] 反素数

Description

  对于任何正整数x,其约数的个数记作g(x)。例如g(1)=1、g(6)=4。如果某个正整数x满足:g(x)>g(i) 0<i<x,则称x为反质数。例如,整数1,2,4,6等都是反质数。现在给定一个数N,你能求出不超过N的最大的反质数么?

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[bzoj 1051][HAOI2006] 受欢迎的牛

Description

  每一头牛的愿望就是变成一头最受欢迎的牛。现在有N头牛,给你M对整数(A,B),表示牛A认为牛B受欢迎。 这种关系是具有传递性的,如果A认为B受欢迎,B认为C受欢迎,那么牛A也认为牛C受欢迎。你的任务是求出有多少头牛被所有的牛认为是受欢迎的。

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AOJ Challenge Problems 1

Anagrammatic Primes

A number is "prime" if it has no divisors other than itself and 1. For example, 23 is prime but 35 is not prime because 35 = 7 x 5. If the digits of a number are rearranged, then usually its primeness changes — for example, 35 is not prime but 53 is. For this problem, you must find numbers which are prime no matter how you rearrange their digits. For example, all of the numbers 113, 131 and 311 are prime, so we say that 113 is an "anagrammatic prime" (also 131 and 311 are anagrammatic primes).

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[hdu 3555] bomb

Problem Description

The counter-terrorists found a time bomb in the dust. But this time the terrorists improve on the time bomb. The number sequence of the time bomb counts from 1 to N. If the current number sequence includes the sub-sequence "49", the power of the blast would add one point.
Now the counter-terrorist knows the number N. They want to know the final points of the power. Can you help them?

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[hdu 2089] 不要62

Problem Description

杭州人称那些傻乎乎粘嗒嗒的人为62(音:laoer)。
杭州交通管理局经常会扩充一些的士车牌照,新近出来一个好消息,以后上牌照,不再含有不吉利的数字了,这样一来,就可以消除个别的士司机和乘客的心理障碍,更安全地服务大众。
不吉利的数字为所有含有4或62的号码。例如:
62315 73418 88914
都属于不吉利号码。但是,61152虽然含有6和2,但不是62连号,所以不属于不吉利数字之列。
你的任务是,对于每次给出的一个牌照区间号,推断出交管局今次又要实际上给多少辆新的士车上牌照了。

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AIO2012 Solution(Chinese)

NORT

It is the year 1982. Malcolm Fraser is the Prime Minister of Australia, you frequently listen to Down Under by Men at Work on your boombox and roller blading is the default mode of transport. As a budding computer scientist, you spend most weekends at the local arcade trying to top your score in the popular video game NORT.

NORT is played on a rectangular grid of square cells with H columns and W rows. You ride a light-bike through the grid, starting in the top-left corner cell. Each second, you can move your light-bike up, down, left or right to any of the four adjacent grid cells (as long as you don't go off the grid!). As you move, your bike's exhaust pipe creates an impenetrable wall of light in the cell you were previously in. If you ever move into a cell containing a wall of light (i.e. a cell you have travelled through before), your bike will disintegrate into pixels in a dramatic 8-bit explosion. The only exception is if you return to the top-left corner cell where you started, in which case the wall of light will be connected and your score for the game will be the total length of wall you have created.

Your goal is therefore to plan the longest possible route through the grid starting and ending in the top-left cell without ever passing through a cell more than once.

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