feat: solve No.389,905

Author: BaffinLee

301-400/389. Find the Difference.md

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+# 389. Find the Difference
+
+- Difficulty: Easy.
+- Related Topics: Hash Table, String, Bit Manipulation, Sorting.
+- Similar Questions: Single Number.
+
+## Problem
+
+You are given two strings `s` and `t`.
+
+String `t` is generated by random shuffling string `s` and then add one more letter at a random position.
+
+Return the letter that was added to `t`.
+
+ 
+Example 1:
+
+```
+Input: s = "abcd", t = "abcde"
+Output: "e"
+Explanation: 'e' is the letter that was added.
+```
+
+Example 2:
+
+```
+Input: s = "", t = "y"
+Output: "y"
+```
+
+ 
+**Constraints:**
+
+
+	
+- `0 <= s.length <= 1000`
+	
+- `t.length == s.length + 1`
+	
+- `s` and `t` consist of lowercase English letters.
+
+
+
+## Solution 1
+
+```javascript
+/**
+ * @param {string} s
+ * @param {string} t
+ * @return {character}
+ */
+var findTheDifference = function(s, t) {
+    var num = 0;
+    for (var i = 0; i < t.length; i++) {
+        num += t[i].charCodeAt(0);
+    }
+    for (var j = 0; j < s.length; j++) {
+        num -= s[j].charCodeAt(0);
+    }
+    return String.fromCharCode(num);
+};
+```
+
+**Explain:**
+
+nope.
+
+**Complexity:**
+
+* Time complexity : O(n).
+* Space complexity : O(1).
+
+## Solution 2
+
+```javascript
+/**
+ * @param {string} s
+ * @param {string} t
+ * @return {character}
+ */
+var findTheDifference = function(s, t) {
+    var num = 0;
+    for (var i = 0; i < t.length; i++) {
+        num ^= t[i].charCodeAt(0);
+    }
+    for (var j = 0; j < s.length; j++) {
+        num ^= s[j].charCodeAt(0);
+    }
+    return String.fromCharCode(num);
+};
+```
+
+**Explain:**
+
+nope.
+
+**Complexity:**
+
+* Time complexity : O(n).
+* Space complexity : O(1).

901-1000/905. Sort Array By Parity.md

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+# 905. Sort Array By Parity
+
+- Difficulty: Easy.
+- Related Topics: Array, Two Pointers, Sorting.
+- Similar Questions: Sort Even and Odd Indices Independently, Largest Number After Digit Swaps by Parity.
+
+## Problem
+
+Given an integer array `nums`, move all the even integers at the beginning of the array followed by all the odd integers.
+
+Return ****any array** that satisfies this condition**.
+
+ 
+Example 1:
+
+```
+Input: nums = [3,1,2,4]
+Output: [2,4,3,1]
+Explanation: The outputs [4,2,3,1], [2,4,1,3], and [4,2,1,3] would also be accepted.
+```
+
+Example 2:
+
+```
+Input: nums = [0]
+Output: [0]
+```
+
+ 
+**Constraints:**
+
+
+	
+- `1 <= nums.length <= 5000`
+	
+- `0 <= nums[i] <= 5000`
+
+
+
+## Solution
+
+```javascript
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var sortArrayByParity = function(nums) {
+    var right = nums.length - 1;
+    var i = 0;
+    while (i < right) {
+        if (nums[i] % 2) {
+            swap(nums, i, right);
+            right--;
+        } else {
+            i++;
+        }
+    }
+    return nums;
+};
+
+var swap = function(nums, i, j) {
+    var tmp = nums[i];
+    nums[i] = nums[j];
+    nums[j] = tmp;
+};
+```
+
+**Explain:**
+
+nope.
+
+**Complexity:**
+
+* Time complexity : O(n).
+* Space complexity : O(1).