Java中的七种排序方式代码示例

Posted 2020-11-02 donsenchen

package baseJava;

/**
 * @title SortMethods.java
 * @author DonsenChen
 * @Date 2018年5月2日 上午10:16:03
 * @Description
 */
public class SortMethods {
    public static void main(String[] args) {
        int[] arr = { 3, 7, 9, 1, 4, 8, 2, 6, 5 };
        binarySort(arr);
        bubbleSort(arr);
        quickSort(arr, 0, 0);
        selectSort(arr);
        insertSort(arr);
        shellSort(arr);
        mergeSort(arr, 0, 0);
    }

    // 1. 二分法排序
    public static void binarySort(int[] numbers) {
        int i, j, temp;
        int low, hight, mid;
        for (i = 1; i < numbers.length; i++) {
            temp = numbers[i];
            low = 0;
            hight = i - 1;
            while (low <= hight) {
                mid = (low + hight) / 2;
                if (numbers[mid] > temp)
                    hight = mid - 1;
                else
                    low = mid + 1;
            }
            for (j = i - 1; j > hight; j--)
                numbers[j + 1] = numbers[j];
            numbers[hight + 1] = temp;
        }
        System.out.print("二分法排序：");
        printArr(numbers);
        System.out.println();
    }

    // 2. 冒泡排序
    public static void bubbleSort(int[] numbers) {
        int temp; // 记录临时中间值
        int size = numbers.length; // 数组大小
        for (int i = 0; i < size - 1; i++) {
            for (int j = i + 1; j < size; j++) {
                if (numbers[i] > numbers[j]) { // 交换两数的位置(ps:这里的大于号小于号决定数组排序的升序或降序)
                    temp = numbers[i];
                    numbers[i] = numbers[j];
                    numbers[j] = temp;
                }
            }
        }
        System.out.print("冒泡排序：");
        printArr(numbers);
        System.out.println();
    }

    // 3. 快速排序
    public static void quickSort(int[] numbers, int start, int end) {
        if (start < end) {
            int base = numbers[start]; // 选定的基准值（第一个数值作为基准值）
            int temp; // 记录临时中间值
            int i = start, j = end;
            do {
                while ((numbers[i] < base) && (i < end))
                    i++;
                while ((numbers[j] > base) && (j > start))
                    j--;
                if (i <= j) {
                    temp = numbers[i];
                    numbers[i] = numbers[j];
                    numbers[j] = temp;
                    i++;
                    j--;
                }
            } while (i <= j);
            if (start < j)
                quickSort(numbers, start, j);
            if (end > i)
                quickSort(numbers, i, end);
        }
        System.out.print("快速排序：");
        printArr(numbers);
        System.out.println();
    }

    // 4. 选择排序
    public static void selectSort(int[] numbers) {
        int size = numbers.length, temp;
        for (int i = 0; i < size; i++) {
            int k = i;
            for (int j = size - 1; j > i; j--) {
                if (numbers[j] < numbers[k])
                    k = j;
            }
            temp = numbers[i];
            numbers[i] = numbers[k];
            numbers[k] = temp;
        }
        System.out.print("选择排序：");
        printArr(numbers);
        System.out.println();
    }

    // 5. 插入排序
    public static void insertSort(int[] numbers) {
        int size = numbers.length, temp, j;
        for (int i = 1; i < size; i++) {
            temp = numbers[i];
            for (j = i; j > 0 && temp < numbers[j - 1]; j--)
                numbers[j] = numbers[j - 1];
            numbers[j] = temp;
        }
        System.out.print("插入排序：");
        printArr(numbers);
        System.out.println();
    }

    // 6. 希尔排序
    public static void shellSort(int[] numbers) {
        int n = numbers.length;
        // 进行分组，最开始的增量(gap)为数组长度的一半
        for (int gap = n / 2; gap > 0; gap /= 2) {
            // 对各个分组进行插入排序
            for (int i = gap; i < n; i++) {
                // 将art[i]插入到所在分组的正确位置上
                insertI(numbers, gap, i);
            }
        }
        System.out.print("希尔排序：");
        printArr(numbers);
        System.out.println();
    }

    // 希尔排序插入方法
    // 将art[i]插入到所在分组的正确位置上
    private static void insertI(int[] arr, int gap, int i) {
        int inserted = arr[i];
        int j;
        for (j = i - gap; j >= 0 && inserted < arr[j]; j -= gap) {
            arr[j + gap] = arr[j];
        }
        arr[j + gap] = inserted;
    }

    // 7. 归并排序
    public static void mergeSort(int[] numbers, int left, int right) {
        int t = 1;// 每组元素个数
        int size = right - left + 1;
        while (t < size) {
            int s = t;// 本次循环每组元素个数
            t = 2 * s;
            int i = left;
            while (i + (t - 1) < size) {
                merge(numbers, i, i + (s - 1), i + (t - 1));
                i += t;
            }
            if (i + (s - 1) < right)
                merge(numbers, i, i + (s - 1), right);
        }
        System.out.print("归并排序：");
        printArr(numbers);
        System.out.println();
    }

    // 归并算法实现
    private static void merge(int[] data, int p, int q, int r) {
        int[] B = new int[data.length];
        int s = p;
        int t = q + 1;
        int k = p;
        while (s <= q && t <= r) {
            if (data[s] <= data[t]) {
                B[k] = data[s];
                s++;
            } else {
                B[k] = data[t];
                t++;
            }
            k++;
        }
        if (s == q + 1)
            B[k++] = data[t++];
        else
            B[k++] = data[s++];
        for (int i = p; i <= r; i++)
            data[i] = B[i];
    }

    // 打印数组
    private static void printArr(int[] arr) {
        System.out.print("[");
        for (int i = 0; i < arr.length; i++) {
            if (i == arr.length - 1) {
                System.out.print(arr[i] + "]");
            } else {
                System.out.print(arr[i] + ", ");
            }

        }
    }

}

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