java m取n 重复 不重复 排列组合 for循环嵌套递归

1、ackage com.file.read;import java.text.SimpleDateFormat;import java.util.ArrayList;import java.util.Date;import java.util.List;import java.util.Random;public class CharacterCompose public static SimpleDateFormat formatTime = new SimpleDateFormat(yyyy-MM-dd HH:mm:ss SSS);/* */public static void main(S

2、tring args) char chs = a, b, c, 1, 2, 3, 4, 5, d, e, f,g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, 6, 7, 8, 9 ;/char chs = A, B, C, D;/duplicate(chs) ;/notDuplicate(chs);/int a = 1838265625;/Random r = new Random();/duplicate(chs, r.nextInt(a)+1);/long numb = 1;/for(int i = 0; i 6; i

3、+) /numb = numb * chs.length;/System.out.println(重复：+numb);/a = 1168675200;/r = new Random();/notDuplicate(chs, r.nextInt(a)+1);/numb = 1;/for(int i = 0; i 1 & n = chs.length) for(int i = 0; i 1 & n = chs.length) for(int i = 0; i chs.length; i+) total = total+loop(0, chs.length, chs, String.valueOf(

4、chsi), 1, n-1,ifNotSame);desc =重复；if(ifNotSame) desc =不重复；System.out.println(chs.length+ 取+ n + desc + 的排列组合个数为+ total);/for循环嵌套递归public static int loop(int start, int end, char chs, String msg, int loopIndex, int loopEnd,boolean ifNotSame) int total = 0;for(int i = start; i end; i+) if(loopIndex =

5、loopEnd) if(ifNotSame & msg.indexOf(String.valueOf(chsi) != -1) continue;/System.out.println(msg + String.valueOf(chsi);total+; else if(ifNotSame & msg.indexOf(String.valueOf(chsi) != -1) continue;String s = msg + String.va山eOf(chsi);int nextIndex = loopIndex + 1;total = total + loop(start, end, chs

6、, s, nextIndex, loopEnd, ifNotSame);return total;/* 重复 1838265625*/public static void duplicate(char chs, long number) List list = new ArrayList();long n = 0;for(int a = 0; a chs.length; a+) for(int b = 0; b chs.length; b+) long time = System.currentTimeMillis();for(int c = 0; c chs.length; c+) for(

7、int d = 0; d chs.length; d+) for(int e = 0; e chs.length; e+) for(int f = 0; f chs.length; f+) /Strings=String.valueOf(chsa)+String.valueOf(chsb)+String.valueOf(chsc)+String.valueOf(chsd)+String .valueOf(chse)+String.valueOf(chsf);/list.add(s);n+;if(number = n) System.out.println(String.valueOf(chsa

8、)+String.valueOf(chsb)+String.valueOf(chsc)+Strin g.valueOf(chsd)+String.valueOf(chse)+String.valueOf(chsf);/System.out.println(formatTime.format(new Date() + +String.valueOf(chsa)+String.valueOf(chsb) + 耗 时(System.currentTimeMillis()-time);System.out.println(n);/*不重复18382656251168675200*/public sta

9、tic void notDuplicate(char chs, long number) List list = new ArrayList();long n = 0;for(int a = 0; a chs.length; a+) for(int b = 0; b chs.length; b+) if(b = a) continue;long time = System.currentTimeMillis();for(int c = 0; c chs.length; c+) if(c = a | c = b) continue;for(int d = 0; d chs.length; d+)

10、 if(d = c | d = a | d = b) continue;for(int e = 0; e chs.length; e+) if(e = d | e = c | e = a | e = b) continue;for(int f = 0; f chs.length; f+) if(f = e | f = d | f = c | f = a | f = b) continue;/Strings=String.valueOf(chsa)+String.va山eOf(chsb)+String.valueOf(chsc)+String.valueOf(chsd)+String .valueOf(chse)+String.valueOf(chsf);/System.out.println(s);/list.add(s);n+;if(number = n) System.out.println(String.valueOf(chsa)+String.valueOf(chsb)+String.valueOf(chsc)+Strin g.valueOf(chsd)+String.valueOf(chse)+String.valu