Acwing 692. g bus count difference + prefix and

Title Description

https://www.acwing.com/problem/content/description/694/
classical Differential prefixes and subject
Constantly add the same fixed value to all numbers in a range , Finally, find the value of a specific place .
Difference The prefix and seckill

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Ideas

See my previous algorithm ideas ：https://blog.csdn.net/weixin_45798993/article/details/122495960

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Code

#include<iostream>
#include<cstring>
using namespace std;
const int N=5010;
int city[N];
int t,n,a,b,p,c;
int cnt=1;
int main()
{
    
    scanf("%d",&t);
    while(t--)
    {
    
        memset(city,0,sizeof(city));  // Empty the contents of the array 
        scanf("%d",&n);
        for(int i=0;i<n;i++)
        {
    
            scanf("%d%d",&a,&b);
            city[a]++;     // Differential operation 
            city[b+1]--;
        }
        
        for(int i=1;i<=5000;i++) city[i]+=city[i-1];  // Find the prefix and 
        // Note that the upper limit is not n, It is 5000, It's the upper limit of the range 
        scanf("%d",&p);
        printf("Case #%d: ",cnt++);
        for(int i=0;i<p;i++)
        {
    
            scanf("%d",&c);
            printf("%d ",city[c]);
        }
        printf("\n");
    }
    return 0;
}

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