zoukankan      html  css  js  c++  java
  • Codeforces Round #419 (Div. 2) B. Karen and Coffee(经典前缀和)

    To stay woke and attentive during classes, Karen needs some coffee!

    Karen, a coffee aficionado, wants to know the optimal temperature for brewing the perfect cup of coffee. Indeed, she has spent some time reading several recipe books, including the universally acclaimed "The Art of the Covfefe".

    She knows n coffee recipes. The i-th recipe suggests that coffee should be brewed between li and ri degrees, inclusive, to achieve the optimal taste.

    Karen thinks that a temperature is admissible if at least k recipes recommend it.

    Karen has a rather fickle mind, and so she asks q questions. In each question, given that she only wants to prepare coffee with a temperature between a and b, inclusive, can you tell her how many admissible integer temperatures fall within the range?

    Input

    The first line of input contains three integers, nk (1 ≤ k ≤ n ≤ 200000), and q (1 ≤ q ≤ 200000), the number of recipes, the minimum number of recipes a certain temperature must be recommended by to be admissible, and the number of questions Karen has, respectively.

    The next n lines describe the recipes. Specifically, the i-th line among these contains two integers li and ri (1 ≤ li ≤ ri ≤ 200000), describing that the i-th recipe suggests that the coffee be brewed between li and ri degrees, inclusive.

    The next q lines describe the questions. Each of these lines contains a and b, (1 ≤ a ≤ b ≤ 200000), describing that she wants to know the number of admissible integer temperatures between a and b degrees, inclusive.

    Output

    For each question, output a single integer on a line by itself, the number of admissible integer temperatures between a and b degrees, inclusive.

    Examples
    input
    3 2 4
    91 94
    92 97
    97 99
    92 94
    93 97
    95 96
    90 100
    output
    3
    3
    0
    4
    input
    2 1 1
    1 1
    200000 200000
    90 100
    output
    0
    题意:

    给出n个区间,然后进行q次区间查询,问每次查询区间中的数至少在k个区间中出现的个数。

    思路:

    前缀和的经典应用。

    也就是++cnt【l】和--cnt【r+1】,很妙。

     1 #include<iostream>
     2 #include<algorithm>
     3 #include<cstring>
     4 #include<cstdio>
     5 #include<sstream>
     6 #include<vector>
     7 #include<stack>
     8 #include<queue>
     9 #include<cmath>
    10 #include<map>
    11 #include<set>
    12 using namespace std;
    13 typedef long long ll;
    14 typedef pair<int,int> pll;
    15 const int INF = 0x3f3f3f3f;
    16 const int maxn = 200000+5;
    17 
    18 int n, k, q;
    19 int cnt[maxn];
    20 int sum[maxn];
    21 
    22 int main()
    23 {
    24     //freopen("in.txt","r",stdin);
    25     while(~scanf("%d%d%d",&n, &k, &q))
    26     {
    27         memset(cnt,0,sizeof(cnt));
    28         for(int i=0;i<n;i++)
    29         {
    30             int l, r;
    31             scanf("%d%d",&l,&r);
    32             ++cnt[l];
    33             --cnt[r+1];
    34         }
    35 
    36         memset(sum,0,sizeof(sum));
    37         for(int i=1;i<=maxn;i++)
    38         {
    39             cnt[i]+=cnt[i-1];
    40             if(cnt[i]>=k)  sum[i]=1;
    41             sum[i]+=sum[i-1];
    42         }
    43 
    44         while(q--)
    45         {
    46             int l, r;
    47             scanf("%d%d",&l, &r);
    48             printf("%d
    ",sum[r]-sum[l-1]);
    49         }
    50     }
    51     return 0;
    52 }
  • 相关阅读:
    ubuntu 14.4 apache2 django
    github上的版本和本地版本冲突的解决方法
    Javascript能做什么 不能做什么。
    django 取model字段的verbose_name值
    Django在admin模块中显示auto_now_add=True或auto_now=True的时间类型列
    合并多个python list以及合并多个 django QuerySet 的方法
    摘抄
    Python 字符串拼接
    学习HTTP
    Django 自定义模板标签和过滤器
  • 原文地址:https://www.cnblogs.com/zyb993963526/p/7082497.html
Copyright © 2011-2022 走看看