1012 The Best Rank （25 分）

To evaluate the performance of our first year CS majored students, we consider their grades of three courses only: C - C Programming Language, M - Mathematics (Calculus or Linear Algrbra), and E - English. At the mean time, we encourage students by emphasizing on their best ranks -- that is, among the four ranks with respect to the three courses and the average grade, we print the best rank for each student.

For example, The grades of C, M, E and A - Average of 4 students are given as the following:

StudentID  C  M  E  A
310101     98 85 88 90
310102     70 95 88 84
310103     82 87 94 88
310104     91 91 91 91

Then the best ranks for all the students are No.1 since the 1st one has done the best in C Programming Language, while the 2nd one in Mathematics, the 3rd one in English, and the last one in average.

Input Specification:

Each input file contains one test case. Each case starts with a line containing 2 numbers N and M (≤2000), which are the total number of students, and the number of students who would check their ranks, respectively. Then N lines follow, each contains a student ID which is a string of 6 digits, followed by the three integer grades (in the range of [0, 100]) of that student in the order of C

Output Specification:

For each of the M students, print in one line the best rank for him/her, and the symbol of the corresponding rank, separated by a space.

The priorities of the ranking methods are ordered as A > C > M > E. Hence if there are two or more ways for a student to obtain the same best rank, output the one with the highest priority.

If a student is not on the grading list, simply output N/A.

Sample Input:

5 6
310101 98 85 88
310102 70 95 88
310103 82 87 94
310104 91 91 91
310105 85 90 90
310101
310102
310103
310104
310105
999999

具體思路:

使用雜湊表儲存學生4門成績的排名就可以了:

int srank[1000000][4];   //一維陣列代表學號,二維記錄各門課程的排名

讀入學生的成績和資料後,利用雜湊表記錄每門課的排名,排名記錄演算法如下:

int re = 1;
		for (int i = 0; i < N; ++i) {
			if (i > 0 && Students[i].grades[now] != Students[i - 1].grades[now]) {
				re = i + 1;
			}
			srank[Students[i].id][now] = re;
		}

查詢的話利用雜湊表查詢即可

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <algorithm>
#include <cmath>
using namespace std;

struct Student {
	int id;
	int grades[4];
}Students[2010];
//新技能,利用雜湊表進行查詢
int srank[1000000][4];   //雜湊表
char Course[4] = { 'A','C','M','E' };
int now;
bool cmp(Student a, Student b) {
	return a.grades[now] > b.grades[now];
}
int queres[2010];
int main() {
	memset(srank, 0, sizeof(srank));
	int N, M;
	scanf("%d %d", &N, &M);
	for (int i = 0; i < N; ++i) {
		scanf("%d %d %d %d", &Students[i].id, &Students[i].grades[1], &Students[i].grades[2], &Students[i].grades[3]);
		Students[i].grades[0] = round((Students[i].grades[1] + Students[i].grades[2] + Students[i].grades[3]) / 3.0)+0.5;
	}

	for (now = 0; now < 4; ++now) {
		sort(Students, Students + N, cmp);
		int re = 1;
		for (int i = 0; i < N; ++i) {
			if (i > 0 && Students[i].grades[now] != Students[i - 1].grades[now]) {
				re = i + 1;
			}
			srank[Students[i].id][now] = re;
		}
	}
	//查詢操作
	for (int i = 0; i < M; ++i) {
		scanf("%d", &queres[i]);
	}
	for (int i = 0; i < M; ++i) {
		if (srank[queres[i]][0] == 0) {
			printf("N/A\n");
			continue;
		}

		int k = 0;
		for (int j = 0; j < 4; ++j) {
			if (srank[queres[i]][j] <srank[queres[i]][k]) {
				k = j;
			}
		}
		printf("%d %c\n", srank[queres[i]][k], Course[k]);
	}
	system("PAUSE");
	return 0;
}