zoukankan      html  css  js  c++  java
  • Margarite and the best present

    Little girl Margarita is a big fan of competitive programming. She especially loves problems about arrays and queries on them.

    Recently, she was presented with an array aa of the size of 109109 elements that is filled as follows:

    a1=−1
    a2=2
    a3=−3
    a4=4
    a5=−5
    And so on ...
    That is, the value of the ii-th element of the array aa is calculated using the formula ai=i⋅(−1)iai=i⋅(−1)i.

    She immediately came up with qq queries on this array. Each query is described with two numbers: ll and rr. The answer to a query is the sum of all the elements of the array at positions from ll to rr inclusive.

    Margarita really wants to know the answer to each of the requests. She doesn't want to count all this manually, but unfortunately, she couldn't write the program that solves the problem either. She has turned to you — the best programmer.

    Help her find the answers!

    Input

    The first line contains a single integer qq (1≤q≤1031≤q≤103) — the number of the queries.

    Each of the next qq lines contains two integers ll and rr (1≤l≤r≤1091≤l≤r≤109) — the descriptions of the queries.

    Output

    Print qq lines, each containing one number — the answer to the query.

    Example

    input

    Copy

    5
    1 3
    2 5
    5 5
    4 4
    2 3
    output

    Copy

    -2
    -2
    -5
    4
    -1
    Note

    In the first query, you need to find the sum of the elements of the array from position 11 to position 33. The sum is equal to a1+a2+a3=−1+2−3=−2a1+a2+a3=−1+2−3=−2.

    In the second query, you need to find the sum of the elements of the array from position 22 to position 55. The sum is equal to a2+a3+a4+a5=2−3+4−5=−2a2+a3+a4+a5=2−3+4−5=−2.

    In the third query, you need to find the sum of the elements of the array from position 55 to position 55. The sum is equal to a5=−5a5=−5.

    In the fourth query, you need to find the sum of the elements of the array from position 44 to position 44. The sum is equal to a4=4a4=4.

    In the fifth query, you need to find the sum of the elements of the array from position 22 to position 33. The sum is equal to a2+a3=2−3=−1a2+a3=2−3=−1.

    题解:对于多种情况考虑分析即可


    ---------------------
    作者:black_hole6
    来源:CSDN
    原文:https://blog.csdn.net/lbperfect123/article/details/84449954
    版权声明:本文为博主原创文章,转载请附上博文链接!

    #include<cstdio>
    #include<algorithm>
    #include<cstring>
    #include<iostream>
    using namespace std;
     
    int main()
    {
        int n;
        cin>>n;
     
        for(int t=0;t<n;t++)
        {
            int a,b;
            long long int sum;
            scanf("%d%d",&a,&b);
            if(a%2==1&&b%2==1)
            {
                sum=-1*((a-b)/2+b);
            }
            else if(a%2==1&&b%2==0)
            {
                sum=(b-a+1)/2;
            }
            else if(a%2==0&&b%2==1)
            {
                sum=-1*(b-a+1)/2;
            }
            else
            {
                sum=(a-b)/2+b;
            }
            printf("%lld
    ",sum);
            
        }
        return 0;
     } 
  • 相关阅读:
    php 单双引号的区别
    SpringBoot动态代理使用Cglib还是jdk的问题
    SpringBoot MyBatis 一级缓存和二级的配置理解
    SpringBoot+MyBatis,显示SQL方式
    java lambda分页
    关于Spring的@Value注解使用Integer方式
    mysql死锁,等待资源,事务锁,Lock wait timeout exceeded; try restarting transaction解决
    关于Integer包装类对象之间值的比较
    你未必了解的DNS
    SpringCloudConfig报错Cannot clone or checkout repository:https://gitee.com/yanfa401/config-repo
  • 原文地址:https://www.cnblogs.com/Staceyacm/p/10012742.html
Copyright © 2011-2022 走看看