计算一组数字的可能排列 [英] Calculate possible permutations of an array of numbers

问题描述

我有一个NSArray的数字{0,1,2,3}

计算4的阶乘（数组数），我有24可能的排列组合0,1,2,3

我想知道是否有办法计算所有这些可能的排列，并将它们放在一个单独的数组中。例如，给定上面的数字{0,1,2,3}，结果排列如下：

  0123,0132,0213,0231,0312,0321，
 1023,1032,1203,1230,1302,1320，
 2013,2031,2103 ，2130,2301,2310，
 3012,3021,3102,3120,3201,3210 
  

任何帮助，非常感谢。非常感谢！

解决方案

我正在寻找代码，但我设法弄清楚:)如果有人需要它，代码如下：

  static NSMutableArray * results; 
 
 void doPermute（NSMutableArray * input，NSMutableArray * output，NSMutableArray * used，int size，int level）{
 if（size == level）{
 NSString * word = [输出componentsJoinedByString：@]; 
 [results addObject：word]; 
 return; 
} 
 
 ++ ++; 
 $ b为（int i = 0; i< input.count; i ++）{
 if（[used [i] boolValue]）{
 continue; 
} 
 
 used [i] = [NSNumber numberWithBool：YES]; 
 [output addObject：input [i]]; 
 doPermute（输入，输出，已用，大小，等级）; 
 used [i] = [NSNumber numberWithBool：NO]; 
 [output removeLastObject]; 
 
 
 
 NSArray * getPermutations（NSString * input，int size）{
 results = [[NSMutableArray alloc] init]; 
 
 NSMutableArray * chars = [[NSMutableArray alloc] init]; 
 
 $ b for（int i = 0; i< [input length]; i ++）{
 NSString * ichar = [NSString stringWithFormat：@％c，[input characterAtIndex：ⅰ]]; 
 [chars addObject：ichar]; 
 
 
 NSMutableArray * output = [[NSMutableArray alloc] init]; 
 NSMutableArray * used = [[NSMutableArray alloc] init]; 
 
（int i = 0; i  [使用的addObject：[NSNumber numberWithBool：NO]]; 
 
 
 doPermute（chars，output，used，size，0）; 
 
返回结果; 
 
 $ / code> 

使用



getPermutations（input，size）

获取一个存储了排列的NSArray。 b
$ b

例如：



  NSLog（@％@，getPermutations（@0123 ，4））; 
 
 //控制台记录
结果:( 
 0123，
 0132，
 0213，
 0231，
 0312，
 0321，
 1023，
 1032，
 1203，
 1230，
 1302，
 1320，
 2013，
 2031，
 2103，
 2130，
 2301，
 2310，
 3012，
 3021，
 3102，
 3120 ，
 3201，
 3210 
）
  

我现在：）


I have an NSArray with the numbers {0,1,2,3}

Calculating the factorial of 4 (the count of the array), I have 24 possible permutations of 0,1,2,3

I would like to know if there is a way to calculate all of these possible permutations and place them in a separate array.

For example, given the numbers above, {0,1,2,3}, the resulting permutations would be:

0123, 0132, 0213, 0231, 0312, 0321,
1023, 1032, 1203, 1230, 1302, 1320,
2013, 2031, 2103, 2130, 2301, 2310,
3012, 3021, 3102, 3120, 3201, 3210

Any help is greatly appreciated. Thank you so much!

解决方案

I was looking for code, but I managed to figure it out :) If anyone else needs it, the code is as follows:

static NSMutableArray *results;

void doPermute(NSMutableArray *input, NSMutableArray *output, NSMutableArray *used, int size, int level) {
    if (size == level) {
        NSString *word = [output componentsJoinedByString:@""];
        [results addObject:word];
        return;
    }

    level++;

    for (int i = 0; i < input.count; i++) {
        if ([used[i] boolValue]) {
            continue;
        }

        used[i] = [NSNumber numberWithBool:YES];
        [output addObject:input[i]];
        doPermute(input, output, used, size, level);
        used[i] = [NSNumber numberWithBool:NO];
        [output removeLastObject];
    }
}

NSArray *getPermutations(NSString *input, int size) {
    results = [[NSMutableArray alloc] init];

    NSMutableArray *chars = [[NSMutableArray alloc] init];


    for (int i = 0; i < [input length]; i++) {
        NSString *ichar  = [NSString stringWithFormat:@"%c", [input characterAtIndex:i]];
        [chars addObject:ichar];
    }

    NSMutableArray *output = [[NSMutableArray alloc] init];
    NSMutableArray *used = [[NSMutableArray alloc] init];

    for (int i = 0; i < chars.count; i++) {
        [used addObject:[NSNumber numberWithBool:NO]];
    }

    doPermute(chars, output, used, size, 0);

    return results;
}

use

getPermutations(input, size)

to get an NSArray with the permutations stored.

For Example:

NSLog(@"%@", getPermutations(@"0123", 4));

//console log
RESULTS: (
    0123,
    0132,
    0213,
    0231,
    0312,
    0321,
    1023,
    1032,
    1203,
    1230,
    1302,
    1320,
    2013,
    2031,
    2103,
    2130,
    2301,
    2310,
    3012,
    3021,
    3102,
    3120,
    3201,
    3210
)

It's working perfect for me now :)

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