anagram

.classpath

@@ -2,5 +2,7 @@
 <classpath>
 	<classpathentry kind="src" path="src"/>
 	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6"/>
+	<classpathentry kind="lib" path="libs/algs4.jar"/>
+	<classpathentry kind="lib" path="libs/stdlib.jar"/>
 	<classpathentry kind="output" path="bin"/>
 </classpath>

.settings/org.eclipse.core.resources.prefs

@@ -1,3 +1,2 @@
-#Sun Jul 29 08:17:20 CST 2012
 eclipse.preferences.version=1
-encoding//src/com/interview/algorithms/array/RandomShuffle.java=UTF-8
+encoding/README=UTF-8

README

@@ -12,7 +12,7 @@ C1: General
     3) Write a function f(a, b) which takes two character string arguments and returns a string containing only the characters found in both strings in the order of a. Write a version which is order N-squared and one which is order N.
     4) Write a function (with helper functions if needed) called to Excel that takes an excel column value (A,B,C,D��A,AB,AC,��AAA..) and returns a corresponding integer value (A=1,B=2,��AA=26..).
     5) You have a stream of infinite queries (ie: real time Google search queries that people are entering). Describe how you would go about finding a good estimate of 1000 samples from this never ending set of data and then write code for it.
-    6) Write some code to reverse a string.
+
     7) Write some code to find all permutations of the letters in a particular string.
     8) What method would you use to look up a word in a dictionary?
     9) You have eight balls all of the same size. 7 of them weigh the same, and one of them weighs slightly more. How can you fine the ball that is heavier by using a balance and only two weighings?
@@ -26,8 +26,7 @@ C1: General
     17) Given a set of coin denominators, find the minimum number of coins to give a certain amount of change.
     18) Given that you have one string of length N and M small strings of length L. How do you efficiently find the occurrence of each small string in the larger one?
     19) How would you reverse the image on an n by n matrix where each pixel is represented by a bit?
-    20) Rotate a string
-    21) Rote an array
+
     22) How to find the median among the given numbers whose values are unknown but falls into a narrow range.
     23) Given a set of ranges, find the two ranges with the greatest overlap.
     24) Verify whether an arithmatic expression is valid, suppose the expression only contains "+", "-", "*", "/", "(", ")" and numbers are integers.
@@ -69,6 +68,7 @@ C4: Array
    13) Given an array containing both positive and negative numbers, find the sub array whose elements' sum is maximum.
    14) Given a set S, find all the maximal subsets whose sum <= k.
    15) Find the uniq amount of absolute values in a given sorted array
+   16) Write code to reverse a array of int
 
 C5: Tree
     1) Describe the algorithm for a depth-first graph traversal.
@@ -103,4 +103,5 @@ C10: System Design
 C11: String
 	1) Implement an algorithm to determine if a string contains all 26 characters. What if you can not use additional data structures?
 	2) Implement an algorithm to determine if a string has all unique characters. What if you can not use additional data structures?
-
+	   Addition, remove all the duplicate characters
+	3) Write a method to decide if two strings are anagrams or not.

src/com/interview/datastructures/string/C11_3_AnagramString.java

@@ -0,0 +1,88 @@
+package com.interview.datastructures.string;
+
+/**
+ * Problem:
+ * 	Write a method to decide if two strings are anagrams or not.
+ * 
+ * Solution:
+ * 	1. sort the two strings, and check if equal
+ * 		time: O(NlogN), space: O(1)
+ *  2. check contained character is same or not
+ *  	time: O(N^2), space: O(1)
+ * @author stefanie
+ *
+ */
+public class C11_3_AnagramString {
+	public boolean check_solution1(String str1, String str2){
+		str1 = sortStr(str1);
+		str2 = sortStr(str2);
+		return str1.equals(str2);
+	}
+
+	public boolean check_solution2(String str1, String str2){
+		char[] arr1 = str1.toCharArray();
+		char[] arr2 = str2.toCharArray();
+
+		for(char ch : arr1){
+			int num1 = 0;
+			for(char ch1 : arr1){
+				if(ch1 == ch) num1++;
+			}
+			int num2 = 0;
+			for(char ch2 : arr2){
+				if(ch2 == ch) num2++;
+			}
+			if(num1 != num2) return false;
+		}
+		return true;
+	}
+
+	public String sortStr(String str){
+		char[] array = str.toCharArray();
+		//quick sort
+		quicksort(array, 0, array.length-1);
+		return String.valueOf(array);
+	}
+
+	public void quicksort(char[] array, int start, int end){
+		if(end <= start) return;
+		int key = partition(array, start, end);
+		quicksort(array, start, key - 1);
+		quicksort(array, key + 1, end);
+	}
+
+	public int partition(char[] array, int start, int end){
+		char key = array[start];
+		int i = start + 1;
+		int j = end;
+		while(true){
+			while(array[i] <= key && i < end) i++;
+			while(array[j] > key && j > start) j--;
+			if(i >= j) break;
+			char temp = array[i];
+			array[i] = array[j];
+			array[j] = temp;
+		}
+		array[start] = array[j];
+		array[j] = key;
+		return j;
+	}
+
+	public static void main(String[] args){
+		C11_3_AnagramString checker = new C11_3_AnagramString();
+		String str1 = "abcde";
+		String str2 = "cdbae";
+		System.out.println(checker.check_solution1(str1, str2));
+		System.out.println(checker.check_solution2(str1, str2));
+
+		String str3 = "abcdeabsyy";
+		String str4 = "bcydybaeas";
+		System.out.println(checker.check_solution1(str3, str4));
+		System.out.println(checker.check_solution2(str3, str4));
+
+		String str5 = "abcdeabsey";
+		String str6 = "bcydybaeas";
+		System.out.println(checker.check_solution1(str5, str6));
+		System.out.println(checker.check_solution2(str5, str6));
+	}
+}