算法3-7：银行排队

#include<bits/stdc++.h>
#define maxn 202 
#define inf 0x3f3f3f3f
using namespace std;
int qu[22]; 
struct node{
	int get;
	int time;
}a[maxn];


int main(){
	int m,total;
	while(cin>>m){
		
	cin>>total;
	for(int i=1;i<=total;i++){
		cin>>a[i].get>>a[i].time;
	}
	memset(qu, 0 ,sizeof qu);
	
	int sum = 0;
	
	for(int i=1;i<=total;i++){//多少人 
	 int pos = inf;
	 int res; 
	 
	 for(int j=1;j<=m;j++){
    	if(qu[j] < pos){//空闲时间长，离开早，遍历找到离开最早的那个 
    		pos = qu[j]; 
    		res = j;
		}
	 }
	 
	 if(a[i].get <  qu[res]){
	 	sum += qu[res] - a[i].get;
	 	qu[res] +=  a[i].time;
	 }
	 
	 else{
	 	qu[res] = a[i].get + a[i].time;
	 }	
	}
	//cout<<sum<<endl;
	printf("%.2lf\n",sum*(1.0)/total*(1.0));
    }
	return 0;
}