commit changes to gh-pages aug 31

Author: tg123

_includes/_root/next-permutation/README.md

@@ -1,4 +1,14 @@
+## [Generation in lexicographic order](http://en.wikipedia.org/wiki/Permutation#Generation_in_lexicographic_order)
 
-## TODO 
-  * write down thinking
+I can not work out this without Google's help.
 
+steps below are copied from Wikipedia:
+
+ 1. Find the largest index k such that a[k] < a[k + 1]. If no such index exists, the permutation is the last permutation.
+ 1. Find the largest index l greater than k such that a[k] < a[l].
+ 1. Swap the value of a[k] with that of a[l].
+ 1. Reverse the sequence from a[k + 1] up to and including the final element a[n].
+
+
+[Fisherlei's Image](http://fisherlei.blogspot.com/2012/12/leetcode-next-permutation.html) is a good illustration. 
+You can see an image that how this solution goes.

_includes/_root/permutations-ii/README.md

@@ -1,4 +1,23 @@
+## Variant of [Next Permutation](../next-permutation)
 
-## TODO 
-  * write down thinking
+With the help of [Next Permutation](../next-permutation), you can find all unique permutations from the first permutation.
 
+### First and Last
+
+ * First permutation is the numbers in non-descending order
+ * Last permutation is the numbers in non-ascending order
+
+
+so the code is like
+
+```
+sort(num) // make it the first
+
+
+while num is not the last
+  call nextPermutation(num)
+  
+  copy num into result
+
+
+```

_includes/_root/permutations-ii/Solution.java

@@ -1,4 +1,5 @@
 public class Solution {
+    
     void swap(int x[], int a, int b) {
     	int t = x[a];
     	x[a] = x[b];
@@ -37,19 +38,18 @@ public boolean nextPermutation(int[] num) {
         return true;
     }    
 
-    ArrayList<Integer> asList(int[] num){
+    List<Integer> asList(int[] num){
         ArrayList<Integer> l = new ArrayList<Integer>(num.length);
         for(int i = 0; i < num.length; i++)
             l.add(num[i]);
 
         return l;
     }
 
-    public ArrayList<ArrayList<Integer>> permuteUnique(int[] num) {
-        // Note: The Solution object is instantiated only once and is reused by each test case.
+    public List<List<Integer>> permuteUnique(int[] num) {
         Arrays.sort(num);
 
-        ArrayList<ArrayList<Integer>> found = new ArrayList<ArrayList<Integer>>();
+        ArrayList<List<Integer>> found = new ArrayList<List<Integer>>();
         found.add(asList(num));
 
         while(nextPermutation(num)){
@@ -58,4 +58,4 @@ public ArrayList<ArrayList<Integer>> permuteUnique(int[] num) {
 
         return found;
     }
-}
+}

next-permutation/index.md

@@ -1,7 +1,7 @@
 ---
 layout: solution
 title: Next Permutation
-date: 2014-07-23 02:42:48 +0800
+date: 2014-08-31 00:42:19 +0800
 ---
 {% assign leetcode_name = {{page.path | remove: '/index.md'}}  %}
 {% assign leetcode_readme = {{leetcode_name | append: '/README.md' | prepend: '_root/' }}  %}

permutations-ii/index.md

@@ -1,7 +1,7 @@
 ---
 layout: solution
 title: Permutations II
-date: 2014-07-23 02:42:48 +0800
+date: 2014-08-31 00:52:32 +0800
 ---
 {% assign leetcode_name = {{page.path | remove: '/index.md'}}  %}
 {% assign leetcode_readme = {{leetcode_name | append: '/README.md' | prepend: '_root/' }}  %}