permutation

README.md

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+Terms:
+Permutation - the act of arranging all the members of a set into some sequence or order, or if the set is already ordered, rearranging (reordering) its elements, a process called permuting.

concepts/1_arrays_and_strings/permutation/README.md

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+These programs will check if a string is a permutation of another.
+
+Things one should consider:
+* case sensitive? - yes
+* whitespace? - yes
+
+Further questions I thought about:
+* Would returning a string vs an array slow the program down?

concepts/1_arrays_and_strings/permutation/permutation.php

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+<?php
+
+echo permutation( 'abcdefg', 'gfedcba' ) . "\n"; // true
+echo permutation( 'abcdefg', 'gfedcbaa' ) . "\n"; // false
+echo permutation( 'a', 'gafaefoaiwehraoiehjfrpawhefrlfedcbaa' ) . "\n"; // false
+
+function permutation( $string1, $string2 ) {
+	if ( strlen( $string1 ) !== strlen( $string2 ) ) {
+		return 'false';
+	}
+
+	if ( string_to_sorted_array( $string1 ) !== string_to_sorted_array( $string2 ) ) {
+		return 'false';
+	}
+
+	return 'true';
+}
+
+function string_to_sorted_array( $string ) {
+	$chars = array();
+	for ( $i = 0; $i <= $strlen - 1; $i++ ) {
+		$chars[ $i ] = substr( $string, $i, 1 );
+	}
+	return arsort( $chars );
+}

concepts/1_arrays_and_strings/permutation/permutation.py

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+def permutation( str1, str2 ):
+	if len( str1 ) != len( str2 ):
+		return 'false'
+
+	if word_array_sort(str1) != word_array_sort(str2):
+		return 'false'
+
+	return 'true'
+
+def word_array_sort( str ):
+	return list(str).sort()
+
+print permutation( "abcdefg", "gfedcba" ); # true
+print permutation( "abcdefg", "gfedcbaa" ); # false
+print permutation( "a", "gafaefoaiwehraoiehjfrpawhefrlfedcbaa" ); # false

concepts/1_arrays_and_strings/permutation/permutation2.php

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+<?php
+
+echo permutation( 'abcdefgzzdddd', 'gfedcbazzdddd' ) . "\n"; // true
+echo permutation( 'abcdefg', 'gfedcbaa' ) . "\n"; // false
+echo permutation( 'a', 'gafaefoaiwehraoiehjfrpawhefrlfedcbaa' ) . "\n"; // false
+
+function permutation( $string1, $string2 ) {
+	$strlen1 = strlen( $string1 );
+	if ( $strlen1 !== strlen( $string2 ) ) {
+		return 'false';
+	}
+
+	$array1 = create_array( $string1, $strlen1 );
+	$array2 = create_array( $string2, $strlen1 );
+
+	if ( ! array_compare( $array1, $array2 ) ) {
+		return 'false';
+	}
+
+	return 'true';
+}
+
+function create_array( $string, $strlen ) {
+	$chars = array();
+	for ( $i = 0; $i <= $strlen - 1; $i++ ) {
+		$char = substr( $string, $i, 1 );
+		if ( ! isset( $chars[ $char ] ) ) {
+			$chars[ $char ] = 1;
+		} else {
+			$chars[ $char ]++;
+		}
+	}
+	return $chars;
+}
+
+function array_compare( $array1, $array2 ) {
+	foreach ( $array1 as $key => $value ) {
+		if ( $value !== $array2[ $key ] ) {
+			return false;
+		}
+	}
+	return true;
+}

concepts/1_arrays_and_strings/permutation/permutation3.php

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+<?php
+
+echo permutation( 'abcdefgzzdddd', 'gfedcbazzdddd' ) . "\n"; // true
+echo permutation( 'abcdefg', 'gfedcbaa' ) . "\n"; // false
+echo permutation( 'a', 'gafaefoaiwehraoiehjfrpawhefrlfedcbaa' ) . "\n"; // false
+
+function permutation( $string1, $string2 ) {
+	if ( strlen( $string1 ) !== strlen( $string2 ) ) {
+		return 'false';
+	}
+
+	$array1 = str_split( $string1 );
+	$array2 = str_split( $string2 );
+	$chars  = array(); // TODO ASCII (128)
+
+	foreach ( $array1 as $c ) { // count
+		$chars[ $c ]++;
+	}
+
+	foreach ( $array2 as $c ) { // reverse
+		$chars[ $c ]--;
+		if ( $chars[ $c ] < 0 ) {
+			return 'false';
+		}
+	}
+
+	return 'true';
+}