feat: add solutions to leetcode problem: No.0561

Author: yanglbme

solution/0500-0599/0561.Array Partition I/README.md

@@ -27,22 +27,52 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
+先排序，然后求相邻的两个元素的最小值，得到的总和即为结果。
+
 <!-- tabs:start -->
 
 ### **Python3**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+class Solution:
+    def arrayPairSum(self, nums: List[int]) -> int:
+        return sum(sorted(nums)[::2])
 ```
 
 ### **Java**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
+class Solution {
+    public int arrayPairSum(int[] nums) {
+        Arrays.sort(nums);
+        int res = 0;
+        for (int i = 0, n = nums.length; i < n; i += 2) {
+            res += nums[i];
+        }
+        return res;
+    }
+}
+```
 
+### **JavaScript**
+
+```js
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var arrayPairSum = function (nums) {
+  nums.sort((a, b) => a - b);
+  let res = 0;
+  for (let i = 0, n = nums.length; i < n; i += 2) {
+    res += nums[i];
+  }
+  return res;
+};
 ```
 
 ### **...**

solution/0500-0599/0561.Array Partition I/README_EN.md

@@ -45,13 +45,41 @@ Given an array of <b>2n</b> integers, your task is to group these integers into
 ### **Python3**
 
 ```python
-
+class Solution:
+    def arrayPairSum(self, nums: List[int]) -> int:
+        return sum(sorted(nums)[::2])
 ```
 
 ### **Java**
 
 ```java
+class Solution {
+    public int arrayPairSum(int[] nums) {
+        Arrays.sort(nums);
+        int res = 0;
+        for (int i = 0, n = nums.length; i < n; i += 2) {
+            res += nums[i];
+        }
+        return res;
+    }
+}
+```
 
+### **JavaScript**
+
+```js
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var arrayPairSum = function (nums) {
+  nums.sort((a, b) => a - b);
+  let res = 0;
+  for (let i = 0, n = nums.length; i < n; i += 2) {
+    res += nums[i];
+  }
+  return res;
+};
 ```
 
 ### **...**

solution/0500-0599/0561.Array Partition I/Solution.java

@@ -0,0 +1,10 @@
+class Solution {
+    public int arrayPairSum(int[] nums) {
+        Arrays.sort(nums);
+        int res = 0;
+        for (int i = 0, n = nums.length; i < n; i += 2) {
+            res += nums[i];
+        }
+        return res;
+    }
+}

solution/0500-0599/0561.Array Partition I/Solution.js

@@ -2,44 +2,11 @@
  * @param {number[]} nums
  * @return {number}
  */
-
-/**
- * Author: Mcnwork2018
- */
-
 var arrayPairSum = function (nums) {
-  let result = merge_sort(nums);
-  let sum = 0;
-  for (let i = 0; i < result.length; i += 2) {
-    sum += result[i];
+  nums.sort((a, b) => a - b);
+  let res = 0;
+  for (let i = 0, n = nums.length; i < n; i += 2) {
+    res += nums[i];
   }
-  return sum;
+  return res;
 };
-function merge_sort(A) {
-  let len = A.length;
-  if (len === 1) return A;
-  let mid = ~~(len / 2);
-  let leftArray = A.slice(0, mid);
-  let rightArray = A.slice(mid, len);
-  return merge(merge_sort(leftArray), merge_sort(rightArray));
-}
-function merge(left, right) {
-  let i = 0,
-    j = 0,
-    k = 0,
-    tmp = [];
-  while (i < left.length && j < right.length) {
-    if (left[i] <= right[j]) {
-      tmp[k++] = left[i++];
-    } else {
-      tmp[k++] = right[j++];
-    }
-  }
-  while (i < left.length) {
-    tmp[k++] = left[i++];
-  }
-  while (j < right.length) {
-    tmp[k++] = right[j++];
-  }
-  return tmp;
-}

solution/0500-0599/0561.Array Partition I/Solution.py

@@ -0,0 +1,3 @@
+class Solution:
+    def arrayPairSum(self, nums: List[int]) -> int:
+        return sum(sorted(nums)[::2])