Merge pull request #86 from nameczz/master

[javascript] 11 & 12 sorts

javascript/11_sorts/sort.js

@@ -0,0 +1,68 @@
+/**
+ * 冒泡，插入，选择排序
+ *
+ * Author: nameczz
+ */
+
+// 冒泡排序
+const bubbleSort = (arr) => {
+    if (arr.length <= 1) return
+    for (let i = 0; i < arr.length; i++) {
+        let hasChange = false
+        for (let j = 0; j < arr.length - i - 1; j++) {
+            if (arr[j] > arr[j + 1]) {
+                const temp = arr[j]
+                arr[j] = arr[j + 1]
+                arr[j + 1] = temp
+                hasChange = true
+            }
+        }
+        // 如果false 说明所有元素已经到位
+        if (!hasChange) break
+    }
+    console.log(arr)
+}
+
+// 插入排序
+const insertionSort = (arr) => {
+    if (arr.length <= 1) return
+    for (let i = 1; i < arr.length; i++) {
+        const temp = arr[i]
+        let j = i - 1
+        // 若arr[i]前有大于arr[i]的值的化，向后移位，腾出空间，直到一个<=arr[i]的值
+        for (j; j >= 0; j--) {
+            if (arr[j] > temp) {
+                arr[j + 1] = arr[j]
+            } else {
+                break
+            }
+        }
+        arr[j + 1] = temp
+    }
+    console.log(arr)
+}
+
+// 选择排序
+const selectionSort = (arr) => {
+    if (arr.length <= 1) return
+    // 需要注意这里的边界, 因为需要在内层进行 i+1后的循环，所以外层需要 数组长度-1
+    for (let i = 0; i < arr.length - 1; i++) {
+        let minIndex = i
+        for (let j = i + 1; j < arr.length; j++) {
+            if (arr[j] < arr[minIndex]) {
+                minIndex = j // 找到整个数组的最小值
+            }
+        }
+        const temp = arr[i]
+        arr[i] = arr[minIndex]
+        arr[minIndex] = temp
+    }
+    console.log(arr)
+}
+
+const test = [4, 5, 6, 3, 2, 1]
+bubbleSort(test)
+const testSort = [4, 1, 6, 3, 2, 1]
+insertionSort(testSort)
+const testSelect = [4, 8, 6, 3, 2, 1, 0, 12]
+selectionSort(testSelect)

javascript/12_sorts/MergeSort.js

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+/**
+ * 归并排序
+ *
+ * Author: nameczz
+ */
+
+const mergeArr = (left, right) => {
+    let temp = []
+    let leftIndex = 0
+    let rightIndex = 0
+    // 判断2个数组中元素大小，依次插入数组
+    while (left.length > leftIndex && right.length > rightIndex) {
+        if (left[leftIndex] <= right[rightIndex]) {
+            temp.push(left[leftIndex])
+            leftIndex++
+        } else {
+            temp.push(right[rightIndex])
+            rightIndex++
+        }
+    }
+    // 合并 多余数组
+    return temp.concat(left.slice(leftIndex)).concat(right.slice(rightIndex))
+}
+
+const mergeSort = (arr) => {
+    // 当任意数组分解到只有一个时返回。
+    if (arr.length <= 1) return arr
+    const middle = Math.floor(arr.length / 2) // 找到中间值
+    const left = arr.slice(0, middle) // 分割数组
+    const right = arr.slice(middle)
+    // 递归 分解 合并
+    return mergeArr(mergeSort(left), mergeSort(right))
+}
+
+const testArr = []
+let i = 0
+while (i < 100) {
+    testArr.push(Math.floor(Math.random() * 1000))
+    i++
+}
+
+const res = mergeSort(testArr)
+console.log(res)

javascript/12_sorts/QuickSort.js

@@ -0,0 +1,46 @@
+/**
+ * 快速排序
+ *
+ * Author: nameczz
+ */
+
+const swap = (arr, i, j) => {
+    const temp = arr[i]
+    arr[i] = arr[j]
+    arr[j] = temp
+}
+
+// 获取 pivot 交换完后的index
+const partition = (arr, pivot, left, right) => {
+    const pivotVal = arr[pivot]
+    let startIndex = left
+    for (let i = left; i < right; i++) {
+        if (arr[i] < pivotVal) {
+            swap(arr, i, startIndex)
+            startIndex++
+        }
+    }
+    swap(arr, startIndex, pivot)
+    return startIndex
+}
+
+const quickSort = (arr, left, right) => {
+    if (left < right) {
+        let pivot = right
+        let partitionIndex = partition(arr, pivot, left, right)
+        quickSort(arr, left, partitionIndex - 1 < left ? left : partitionIndex - 1)
+        quickSort(arr, partitionIndex + 1 > right ? right : partitionIndex + 1, right)
+    }
+
+}
+
+
+const testArr = []
+let i = 0
+while (i < 10) {
+    testArr.push(Math.floor(Math.random() * 1000))
+    i++
+}
+console.log('unsort', testArr)
+quickSort(testArr, 0, testArr.length - 1);
+console.log('sort', testArr)