Permutation 組合筆記

Python

import itertools

print(list(itertools.permutations(['a','b','c'])))

或者直接輸出

python -c "import itertools; print list(itertools.permutations(['a','b','c']))"

PHP

<?php
function combine_chars($items, $combines = array()) {
	static $set;
	
	// Initial set
	if (empty($combines) === true) {
		$set = array();
	}
	
	// Format items type
	if (is_string($items) === true) {
		$items = str_split($items);
	}
	
	// Save combines result
	if (empty($items) === true) {
		array_push($set, join('', $combines));
	}
	
	// Calculate  combines result
	for ($t=count($items)-1, $i=$t; $i>=0; --$i) {
		$temp_items    = $items;
		$temp_combines = $combines;
		
		array_unshift($temp_combines, array_splice($temp_items, $i, 1)[0]);
		combine_chars($temp_items, $temp_combines);
	}
	
	// Return
	return $set;
}

print_r(combine_chars(array('a', 'b', 'c')));
print_r(combine_chars('abc'));