算法竞赛入门经典java版程序ch4 UVa12412

package ch4.uva12412;import java.io.*;import java.util.ArrayList;import java.util.Collections;import java.util.HashMap;import java.util.Scanner;class Student implements Comparable<Student> {String sid;String cid;String name;int chinese;int math;int english;int prog;//int total;float avg;int rank;public String toString() {return rank+" "+sid + " " + cid + " " + name + " " + chinese + " " + math + " " + english + " " + prog + " " + total + " " + String.format("%.2f", avg);}@Overridepublic int compareTo(Student s) {if (this.total > s.total)return -1;else if (this.total < s.total)return 1;elsereturn 0;}}class Main {public static Scanner cin;public static int choice;public static ArrayList<Student> stuList = new ArrayList<Student>();public static ArrayList<Student> stuList2 = new ArrayList<Student>();public static void main(String[] args) throws Exception{showMainUI();cin = new Scanner(System.in);//cin=new Scanner(new BufferedReader(new InputStreamReader(new FileInputStream("12412.in"))));while ((choice = cin.nextInt()) >= 0) {if (choice == 1) {menuAdd();} else if (choice == 2) {menuRemove();} else if (choice == 3) {menuQuery();} else if (choice == 4) {menuShowRanking();} else if (choice == 5) {menuShowStatics();} else {menuExit();}}}// copy stuList到新数组,并计算rankpublic static void copyForRank() {stuList2.clear();for (int i = 0; i < stuList.size(); i++) {stuList2.add(stuList.get(i));}Collections.sort(stuList2);// 升序排序int rank = 0;int k=1;//向后滑几个rank计数int lastTotal = -1;//防止0分出现for (int i = 0; i < stuList2.size(); i++) {if (stuList2.get(i).total != lastTotal) {rank=rank+k;k=1;}else{k++;}stuList2.get(i).rank = rank;lastTotal = stuList2.get(i).total;}}// 根据sid找，如果没找到返回nullpublic static Student findStudentBySid(String sid) {for (int i = 0; i < stuList.size(); i++) {if (sid.equals(stuList.get(i).sid)) {return stuList.get(i);}}return null;}// 根据sid removepublic static int removeStudentBySid(String sid) {int count = 0;for (int i = 0; i < stuList.size(); i++) {if (sid.equals(stuList.get(i).sid)) {stuList.remove(i);i--;count++;}}return count;}// 根据名称查找，如果没找到.list.size()=0public static ArrayList<Student> findStudentByName(String name) {ArrayList<Student> list = new ArrayList<Student>();for (int i = 0; i < stuList.size(); i++) {if (name.equals(stuList.get(i).name)) {list.add(stuList.get(i));}}return list;}// 根据名称removepublic static int removeStudentByName(String name) {int count = 0;for (int i = 0; i < stuList.size(); i++) {if (name.equals(stuList.get(i).name)) {stuList.remove(i);i--;//重要，以防止后面的元素移上来，下一次没有操作count++;}}return count;}// 根据班级号显示统计信息public static void showStatisticsBySid(String cid) {ArrayList<Student> list = new ArrayList<Student>();for (int i = 0; i < stuList.size(); i++) {if (cid.equals(stuList.get(i).cid)) {list.add(stuList.get(i));}}printStatistics(list);}// 找印指定范围的学生统计信息public static void printStatistics(ArrayList<Student> list) {// caculateint sumChn = 0, cntChn = 0;int sumMath = 0, cntMath = 0;int sumEng = 0, cntEng = 0;int sumProg = 0, cntProg = 0;int cntTotal = 0;int[] cntPass = new int[5];for (int i = 0; i < list.size(); i++) {cntTotal = 0;sumChn += list.get(i).chinese;sumMath += list.get(i).math;sumEng += list.get(i).english;sumProg += list.get(i).prog;if (list.get(i).chinese >= 60) {cntChn++;cntTotal++;}if (list.get(i).math >= 60) {cntMath++;cntTotal++;}if (list.get(i).english >= 60) {cntEng++;cntTotal++;}if (list.get(i).prog >= 60) {cntProg++;cntTotal++;}// 计算通过门数if (cntTotal >= 4) {cntPass[0]++;}if (cntTotal >= 3) {cntPass[1]++;}if (cntTotal >= 2) {cntPass[2]++;}if (cntTotal >= 1) {cntPass[3]++;}if (cntTotal == 0) {cntPass[4]++;}}System.out.println("Chinese");System.out.printf("Average Score: %.2f\n", 1.0 * sumChn / list.size());System.out.println("Number of passed students: " + cntChn);System.out.println("Number of failed students: " + (list.size() - cntChn));System.out.println();System.out.println("Mathematics");System.out.printf("Average Score: %.2f\n", 1.0 * sumMath / list.size());System.out.println("Number of passed students: " + cntMath);System.out.println("Number of failed students: " + (list.size() - cntMath));System.out.println();System.out.println("English");System.out.printf("Average Score: %.2f\n", 1.0 * sumEng / list.size());System.out.println("Number of passed students: " + cntEng);System.out.println("Number of failed students: " + (list.size() - cntEng));System.out.println();System.out.println("Programming");System.out.printf("Average Score: %.2f\n", 1.0 * sumProg / list.size());System.out.println("Number of passed students: " + cntProg);System.out.println("Number of failed students: " + (list.size() - cntProg));System.out.println();System.out.println("Overall:");System.out.println("Number of students who passed all subjects: " + cntPass[0]);System.out.println("Number of students who passed 3 or more subjects: " + cntPass[1]);System.out.println("Number of students who passed 2 or more subjects: " + cntPass[2]);System.out.println("Number of students who passed 1 or more subjects: " + cntPass[3]);System.out.println("Number of students who failed all subjects: " + cntPass[4]);}public static void showMainUI() {System.out.println("Welcome to Student Performance Management System (SPMS).");System.out.println();System.out.println("1 - Add");System.out.println("2 - Remove");System.out.println("3 - Query");System.out.println("4 - Show ranking");System.out.println("5 - Show Statistics");System.out.println("0 - Exit");System.out.println();}public static void showAll() {System.out.println("*********");for (int i = 0; i < stuList.size(); i++) {System.out.println(stuList.get(i));}}public static void menuAdd() {cin.nextLine();// 吃回车System.out.println("Please enter the SID, CID, name and four scores. Enter 0 to finish.");String s;while (!(s = cin.nextLine()).equals("0")) {String[] arr = s.split(" ");Student stu = new Student();stu.sid = arr[0];stu.cid = arr[1];stu.name = arr[2];stu.chinese = Integer.valueOf(arr[3]);stu.math = Integer.valueOf(arr[4]);stu.english = Integer.valueOf(arr[5]);stu.prog = Integer.valueOf(arr[6]);stu.total = stu.chinese + stu.math + stu.prog + stu.english;stu.avg = stu.total / 4.0F;// 有点慢？每加一个都要循环去找一遍if (findStudentBySid(stu.sid) != null) {System.out.println("Duplicated SID.");} else {stuList.add(stu);}System.out.println("Please enter the SID, CID, name and four scores. Enter 0 to finish.");}//System.out.println("before rank....add");//showAll();// 计算rankcopyForRank();//System.out.println("after ... rank....add");//showAll();showMainUI();}private static void menuExit() {System.exit(0);}private static void menuShowStatics() {cin.nextLine();// 吃回车 }System.out.println("Please enter class ID, 0 for the whole statistics.");String s = cin.nextLine();if (s.equals("0")) {// allprintStatistics(stuList);} else {// cidshowStatisticsBySid(s);}System.out.println();showMainUI();}private static void menuShowRanking() {System.out.println("Showing the ranklist hurts students' self-esteem. Don't do that.");//showMainUI();}private static void menuQuery() {cin.nextLine();// 吃回车 }System.out.println("Please enter SID or name. Enter 0 to finish.");String s;// 先准备好条件，在查询，更快while (!(s = cin.nextLine()).equals("0")) {if (s.charAt(0) >= '0' && s.charAt(0) <= '9') {// sidStudent stu = findStudentBySid(s);if (stu != null) {System.out.println(stu);}} else {// nameArrayList list = findStudentByName(s);// output,如果没有不输出for (int i = 0; i < list.size(); i++) {System.out.println(list.get(i));}}System.out.println("Please enter SID or name. Enter 0 to finish.");}//showMainUI();}private static void menuRemove() {cin.nextLine();// 吃回车System.out.println("Please enter SID or name. Enter 0 to finish.");String s;// 先准备好条件，在查询，更快while (!(s = cin.nextLine()).equals("0")) {int xx = 0;if (s.charAt(0) >= '0' && s.charAt(0) <= '9') {// sidxx = removeStudentBySid(s);System.out.println(xx + " student(s) removed.");} else {// namexx = removeStudentByName(s);System.out.println(xx + " student(s) removed.");}System.out.println("Please enter SID or name. Enter 0 to finish.");}//System.out.println("before rank....remove");//showAll();//copyForRank();// 重新算rankshowMainUI();//System.out.println("after rank....remove");//showAll();}}