zoukankan      html  css  js  c++  java
  • codechef The Ball And Cups题解

    The Ball And Cups


    At the end of a busy day, The Chef and his assistants play a game together. The game is not just for fun but also used to decide who will have to clean the kitchen. The Chef is a Game Master, so his concern is how to manage the game but not how to win the game like his assistants do.

    The game requires players to find the only ball under one of the N cups after their positions are changed in a special way. At the beginning of the game, The Chef places N cups in a row and put a ball under the C-th cup from the left (the cups are numbered from 1 to N). All players can see the initial position of the ball. Then Chef performs Q flip operations. Each flip operation is defined by two integers L and R such that 1 ≤ L ≤ R ≤ N and consists in reversing the segment [L, R] of cups. Namely, Chef swaps L-th and R-th cups, (L+1)-th and (R−1)-th cups, and so on. After performing all the operations Chef asks his assistants to choose a cup that they think the ball is under it. Who can guess the position of the ball will win the game, and of course, the others will have to clean the kitchen.

    The Chef doesn't want to check all the N cups at the end of the game. He notes down the value of C and the pairs (L, R) and asked you, the mastered programmer, to determine the cup that contains the ball.

    Input

    The first line of the input contains a single integer T, denoting the number of test cases. The description of Ttest cases follows. The first line of each test case contains three space-separated integers NC and Q, denoting the total number of cups, the initial position of the ball and the number of flip operations Chef will perform. Each of the following Q lines contains two space-separated integers L and R, denoting the ends of the segment of the current flip operation.

    Output

    For each test case output on a separate line the final position of the ball.

    Constraints

    • 1 ≤ T ≤ 10
    • 1 ≤ N ≤ 100000 (105)
    • 1 ≤ C ≤ N
    • 1 ≤ Q ≤ 10000 (104)
    • 1 ≤ L ≤ R ≤ N

    Example

    Input:
    1
    5 2 3
    1 4
    3 5
    1 5
    
    Output:
    1

    也是个构造数学公式的样例。

    这里是过万个输入。故此最优点理一下输入,使得程序能够0ms过。

    注意:

    1 陷阱 - C会不在[L, R]范围内

    2 fread处理输入,记得推断最后输入结束的条件 - fread返回长度为零,否则。尽管能够AC。可是程序是有bug的。

    我都使用类当做函数使用了,能够非常好降低变量名的冲突。

    #pragma once
    #include <stdio.h>
    
    class TheBallAndCups
    {
    	int st, len;
    	static const int BU_MAX = 5120;
    	char buffer[BU_MAX];
    
    	char getFromBuffer()
    	{
    		if (st >= len)
    		{
    			len = fread(buffer, 1, BU_MAX, stdin);
    			st = 0;
    		}
    		return buffer[st++];
    	}
    
    	int scanInt()
    	{
    		char c = getFromBuffer();
    		while (c < '0' || '9' < c)
    		{
    			c = getFromBuffer();
    		}
    		int num = 0;
    		while ('0' <= c && c <= '9' && 0 != len)//必需要加0 != len推断输入结束
    		{
    			num = (num<<3) + (num<<1) + (c - '0');
    			c = getFromBuffer();
    		}
    		return num;
    	}
    
    public:
    	TheBallAndCups() : st(0), len(0)
    	{
    		int T = 0, N = 0, C = 0, L = 0, R = 0, Q = 0;
    		T = scanInt();
    		while (T--)
    		{
    			N = scanInt();
    			C = scanInt();
    			Q = scanInt();
    			while (Q--)
    			{
    				L = scanInt();
    				R = scanInt();
    				if (C < L || R < C) continue;
    				int M = L + ((R-L)>>1);				
    				if (C <= M)
    				{
    					int diff = C - L;
    					C = R - diff;
    				}
    				else
    				{
    					int diff = R - C;
    					C = L + diff;
    				}
    			}
    			printf("%d
    ", C);
    		}
    	}
    };
    
    int theBallAndCups()
    {
    	TheBallAndCups();
    	return 0;
    }



  • 相关阅读:
    云端: 小软件大平台,绿色又安全 V0.9 Beta3(090722)
    Kindle 中文阅读终极优化指南
    编辑距离
    在IE中输入网址不能访问,但输入IP地址可以访问,为什么?
    英文缩写解释
    为什么有时上网速度很慢?
    常用命令
    如何使用ping命令检查网络故障
    密码的故事
    提示主机名冲突怎么办?
  • 原文地址:https://www.cnblogs.com/yfceshi/p/6772463.html
Copyright © 2011-2022 走看看