Aizu The Maximum Number of Customers

http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=DSL_5_A The Maximum Number of Customers

Idea: find the most overlapped segment.  Similiar to the line painting

Mark the left and right element, x: L, O: R

#include<cstdio>
#include<cstdlib>
#include<cstring>
using namespace std;
//https://www.hustyx.com/cpp/5/ -- reference
#define N 100005
int a[N];
int main(){
    //input
    freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);
    memset(a,,N);
    int n,t,l,r;
    scanf("%d %d",&n,&t);
    for(int i = ; i<n; i++){
        scanf("%d %d",&l,&r);
        a[l]++;
        a[r]--;
    }
    //preprocess in the array
    int max = ;
    int count = ;
    for(int i = ; i<N; i++){
        count += a[i];
        if(max<count) max = count;
    }
    printf("%d\n",max);
    //printf("wei");
    return ;
}

C++ learning from this code

* redefine the stream from input file

freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);

* memset in cstring