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package class14;
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import java.util.Arrays;
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import java.util.Comparator;
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public class Code03_BestArrange {
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public static class Program {
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public int start;
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public int end;
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public Program(int start, int end) {
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this.start = start;
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this.end = end;
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}
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}
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// 暴力！所有情况都尝试！
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public static int bestArrange1(Program[] programs) {
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if (programs == null || programs.length == 0) {
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return 0;
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}
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return process(programs, 0, 0);
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}
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// 还剩下的会议都放在programs里
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// done之前已经安排了多少会议的数量
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// timeLine目前来到的时间点是什么
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// 目前来到timeLine的时间点，已经安排了done多的会议，剩下的会议programs可以自由安排
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// 返回能安排的最多会议数量
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public static int process(Program[] programs, int done, int timeLine) {
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if (programs.length == 0) {
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return done;
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}
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// 还剩下会议
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int max = done;
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// 当前安排的会议是什么会，每一个都枚举
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for (int i = 0; i < programs.length; i++) {
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if (programs[i].start >= timeLine) {
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Program[] next = copyButExcept(programs, i);
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max = Math.max(max, process(next, done + 1, programs[i].end));
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}
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}
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return max;
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}
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public static Program[] copyButExcept(Program[] programs, int i) {
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Program[] ans = new Program[programs.length - 1];
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int index = 0;
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for (int k = 0; k < programs.length; k++) {
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if (k != i) {
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ans[index++] = programs[k];
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}
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}
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return ans;
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}
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// 会议的开始时间和结束时间，都是数值，不会 < 0
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public static int bestArrange2(Program[] programs) {
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Arrays.sort(programs, new ProgramComparator());
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int timeLine = 0;
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int result = 0;
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// 依次遍历每一个会议，结束时间早的会议先遍历
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for (int i = 0; i < programs.length; i++) {
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if (timeLine <= programs[i].start) {
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result++;
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timeLine = programs[i].end;
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}
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}
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return result;
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}
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public static class ProgramComparator implements Comparator<Program> {
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@Override
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public int compare(Program o1, Program o2) {
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return o1.end - o2.end;
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}
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}
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// for test
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public static Program[] generatePrograms(int programSize, int timeMax) {
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Program[] ans = new Program[(int) (Math.random() * (programSize + 1))];
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for (int i = 0; i < ans.length; i++) {
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int r1 = (int) (Math.random() * (timeMax + 1));
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int r2 = (int) (Math.random() * (timeMax + 1));
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if (r1 == r2) {
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ans[i] = new Program(r1, r1 + 1);
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} else {
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ans[i] = new Program(Math.min(r1, r2), Math.max(r1, r2));
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}
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}
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return ans;
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}
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public static void main(String[] args) {
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int programSize = 12;
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int timeMax = 20;
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int timeTimes = 1000000;
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for (int i = 0; i < timeTimes; i++) {
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Program[] programs = generatePrograms(programSize, timeMax);
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if (bestArrange1(programs) != bestArrange2(programs)) {
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System.out.println("Oops!");
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}
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}
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System.out.println("finish!");
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}
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}
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