482_License_Key_Formatting and 709_To_Lower_Case

qiyuangong · qiyuangong · commit a1ec6f797705 · 2018-11-25T17:16:09.000+08:00
diff --git a/README.md b/README.md
@@ -138,12 +138,14 @@ Remember solutions are only solutions to given problems. If you want full study
 | 453 | [Number of Segments in a String](https://leetcode.com/problems/minimum-moves-to-equal-array-elements/description/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/453_Minimum_Moves_to_Equal_Array_Elements.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/453_Minimum_Moves_to_Equal_Array_Elements.java) | Each move is equal to minus one element in array, so the answer is the sum of all elements after minus min. |
 | 461 | [Hamming Distance](https://leetcode.com/problems/hamming-distance/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/461_Hamming_Distance.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/461_Hamming_Distance.java) | Hamming Distance is related to XOR for numbers. So, XOR then count 1. O(n) |
 | 463 | [Island Perimeter](https://leetcode.com/problems/island-perimeter/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/463_Island_Perimeter.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/463_Island_Perimeter.java) | math, find the area, actual number, then find the digit |
+| 482 | [License Key Formatting](https://leetcode.com/problems/license-key-formatting/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/482_License_Key_Formatting.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/482_License_Key_Formatting.java) | String processing, lower and len % K, O(n) and O(n) |
 | 538 | [Convert BST to Greater Tree](https://leetcode.com/problems/convert-bst-to-greater-tree/description/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/538_Convert_BST_to_Greater_Tree.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/538_Convert_BST_to_Greater_Tree.java) | Right first DFS with a variable recording sum of node.val and right.val. 1. Recursive.<br>2. Stack 3. Reverse Morris In-order Traversal |
 | 543 | [Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree/description/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/543_Diameter_of_Binary_Tree.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/543_Diameter_of_Binary_Tree.java) | DFS with O(1) for max answer |
 | 572 | [Subtree of Another Tree](https://leetcode.com/problems/subtree-of-another-tree/description/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/572_Subtree_of_Another_Tree.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/572_Subtree_of_Another_Tree.java) | 1. Tree traverse and compare<br>2. Tree to string and compare |
 | 581 | [Shortest Unsorted Continuous Subarray](https://leetcode.com/problems/subtree-of-another-tree/description/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/581_Shortest_Unsorted_Continuous_Subarray.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/581_Shortest_Unsorted_Continuous_Subarray.java) | 1. Sort and find the difference (min and max), O(nlgn)<br>2. Using stack to find boundaries (push when correct order, pop when not correct), O(n) and O(n)<br>3. Find min and max of unordered array, O(n) and O(1)|
 | 617 | [Merge Two Binary Trees](https://leetcode.com/problems/merge-two-binary-trees/description/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/617_Merge_Two_Binary_Trees.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/617_Merge_Two_Binary_Trees.java) | Traverse both trees Recursion & Iterative (stack) |
 | 654 | [Maximum Binary Tree](https://leetcode.com/problems/maximum-binary-tree/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/654_Maximum_Binary_Tree.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/654_Maximum_Binary_Tree.java) | 1. Divide and conquer, recursive, O(n^2)<br>2. Monotonic stack, O(n) |
+| 709 | [To Lower Case](https://leetcode.com/problems/to-lower-case/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/709_To_Lower_Case.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/709_To_Lower_Case.java) | String processing:<br>1. str.lower() or str.toLowerCase()<br>2. ASCII processing. O(n) and O(1) |
 | 716 | [Max Stack](https://leetcode.com/problems/max-stack/) &hearts; | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/716_Max_Stack.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/716_Max_Stack.java) | 1. Two stacks<br> 2. Double linked list and Hash |
 | 771 | [Jewels and Stones](https://leetcode.com/problems/jewels-and-stones/description/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/771_Jewels_and_Stones.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/771_Jewels_and_Stones.java) | Count given char in string. Hash or table. [Oneline](https://leetcode.com/problems/jewels-and-stones/discuss/113574/1-liners-PythonJavaRuby) |
 | 804 | [Unique Morse Code Words](https://leetcode.com/problems/unique-morse-code-words/description/) | [Python](https://github.com/qiyuangong/leetcode/blob/master/python/804_Unique_Morse_Code_Words.py) [Java](https://github.com/qiyuangong/leetcode/blob/master/java/804_Unique_Morse_Code_Words.java) | String, Hash and Set. Set is recommended. |
diff --git a/java/482_License_Key_Formatting.java b/java/482_License_Key_Formatting.java
@@ -0,0 +1,10 @@
+class Solution {
+    public String licenseKeyFormatting(String s, int k) {
+        // https://leetcode.com/problems/license-key-formatting/discuss/96512/Java-5-lines-clean-solution
+        StringBuilder sb = new StringBuilder();
+        for (int i = s.length() - 1; i >= 0; i--)
+            if (s.charAt(i) != '-')
+                sb.append(sb.length() % (k + 1) == k ? '-' : "").append(s.charAt(i));
+        return sb.reverse().toString().toUpperCase();
+    } 
+}
diff --git a/java/709_To_Lower_Case.java b/java/709_To_Lower_Case.java
@@ -0,0 +1,13 @@
+class Solution {
+    public String toLowerCase(String str) {
+        return str.toLowerCase();
+    }
+
+    /*public String toLowerCase(String str) {
+        char[] a = str.toCharArray();
+        for (int i = 0; i < a.length; i++)
+            if ('A' <= a[i] && a[i] <= 'Z')
+                a[i] = (char) (a[i] - 'A' + 'a');
+        return new String(a);
+    }*/
+}
diff --git a/python/482_License_Key_Formatting.py b/python/482_License_Key_Formatting.py
@@ -0,0 +1,19 @@
+class Solution(object):
+    def licenseKeyFormatting(self, S, K):
+        """
+        :type S: str
+        :type K: int
+        :rtype: str
+        """
+        # https://leetcode.com/problems/license-key-formatting/discuss/96497/Python-solution
+        S = S.upper().replace('-', '')
+        ls = len(S)
+        if ls % K == 0:
+            pos = K
+        else:
+            pos = ls % K
+        res = S[:pos]
+        while pos < ls:
+            res += '-' + S[pos:pos + K]
+            pos += K
+        return res
diff --git a/python/709_To_Lower_Case.py b/python/709_To_Lower_Case.py
@@ -0,0 +1,17 @@
+class Solution(object):
+    def toLowerCase(self, str):
+        """
+        :type str: str
+        :rtype: str
+        """
+        res = []
+        gap = ord('a') - ord('A')
+        for c in str:
+            if ord(c) >= ord('A') and ord(c) <= ord('Z'):
+                res.append(chr(ord(c) + gap))
+            else:
+                res.append(c)
+        return ''.join(res)
+
+    # def toLowerCase(self, str):
+    #     return str.lower()
