1141 PAT Ranking of Institutions (25分) C++ (hash)

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本文介绍了一种基于学生表现的PAT竞赛机构排名系统的实现方法，通过解析输入数据，使用哈希表记录每位考生的成绩和所属机构，最终生成按加权总分排序的机构排名列表。系统考虑了不同级别考试成绩的权重，并在排名相同的情况下，按照考生人数和机构代码的字母顺序进行排序。

After each PAT, the PAT Center will announce the ranking of institutions based on their students’ performances. Now you are asked to generate the ranklist.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (≤10
5), which is the number of testees. Then N lines follow, each gives the information of a testee in the following format:

ID Score School

where ID is a string of 6 characters with the first one representing the test level: B stands for the basic level, A the advanced level and T the top level; Score is an integer in [0, 100]; and School is the institution code which is a string of no more than 6 English letters (case insensitive). Note: it is guaranteed that ID is unique for each testee.

Output Specification:

For each case, first print in a line the total number of institutions. Then output the ranklist of institutions in nondecreasing order of their ranks in the following format:

Rank School TWS Ns

where Rank is the rank (start from 1) of the institution; School is the institution code (all in lower case); ; TWS is the total weighted score which is defined to be the integer part of ScoreB/1.5 + ScoreA + ScoreT*1.5, where ScoreX is the total score of the testees belong to this institution on level X; and Ns is the total number of testees who belong to this institution.

The institutions are ranked according to their TWS. If there is a tie, the institutions are supposed to have the same rank, and they shall be printed in ascending order of Ns. If there is still a tie, they shall be printed in alphabetical order of their codes.

Sample Input:

10
A57908 85 Au
B57908 54 LanX
A37487 60 au
T28374 67 CMU
T32486 24 hypu
A66734 92 cmu
B76378 71 AU
A47780 45 lanx
A72809 100 pku
A03274 45 hypu

Sample Output:

5
1 cmu 192 2
1 au 192 3
3 pku 100 1
4 hypu 81 2
4 lanx 81 2

思路：先定义一个结构体sc，用一个哈希表记录sc的内容，最后用cmp函数进行比较，输出各个学校的情况。

#include<bits/stdc++.h>
using namespace std;
struct sc{
	string name;
	double sum=0;
	int ren=0;
}; 
bool cmp(sc a,sc b)
{
	if(a.sum!=b.sum) return a.sum>b.sum;
	if(a.ren!=b.ren) return a.ren<b.ren;
	return a.name<b.name;
}
int main()
{
    int n; cin>>n;
    map<string,sc> hash;
    while(n--)
    {
    	string num,school,s;
    	double score;
    	cin>>num>>score>>school;
    	for(auto x:school)
    		s+=tolower(x);
    	if(num[0]=='B') hash[s].sum+=score/1.5;
    	else if(num[0]=='A') hash[s].sum+=score;
    	else if(num[0]=='T') hash[s].sum+=score*1.5;
    	hash[s].ren++;
    	hash[s].name=s;
	}
	vector<sc> schools;
	for(auto x:hash){
		x.second.sum=(int)(x.second.sum +1e-8);
		schools.push_back(x.second);
	}
	sort(schools.begin(),schools.end(),cmp);
	cout<<schools.size()<<endl;
	int j=1;
	for(int i=0;i<schools.size();i++)
	{
		if(schools[i].sum!=schools[i-1].sum) j=i+1;
		cout<<j<<" "<<schools[i].name<<" "<<schools[i].sum<<" "<<schools[i].ren<<endl;
	}		
    return 0;
}