1 冒泡排序

package com.xianhuii.sort;

import org.junit.Test;

import java.util.Arrays;

public class BubbleSort {
    private void swap(int[] arr, int i, int j) {
        int tmp = arr[i];
        arr[i] = arr[j];
        arr[j] = tmp;
    }

    public void sort(int[] arr) {
        int len = arr.length;
        boolean flag;
        for (int i = 1; i < len; i++) {
            flag = false;
            for (int j = 0; j < len - i; j++) {
                if (arr[j] > arr[j + 1]) {
                    flag = true;
                    swap(arr, j, j + 1);
                }
            }
            if (!flag) {
                break;
            }
        }
    }

    @Test
    public void test() {
        int[] arr = new int[]{4, 5, 6, 3, 2, 1};
        sort(arr);
        System.out.println(Arrays.toString(arr));
    }
}

2 选择排序

package com.xianhuii.sort;

import org.junit.Test;

import java.util.Arrays;

public class SelectSort {
    private void swap(int[] arr, int i, int j) {
        int tmp = arr[i];
        arr[i] = arr[j];
        arr[j] = tmp;
    }

    public void sort(int[] arr) {
        int len = arr.length;
        int minIndex = 0;
        for (int i = 0; i < len - 1; i++) {
            minIndex = i;
            for (int j = i + 1; j < len; j++) {
                if (arr[j] < arr[minIndex]) {
                    minIndex = j;
                }
            }
            if (minIndex != i) {
                swap(arr, i, minIndex);
            }
        }
    }

    @Test
    public void test() {
        int[] arr = new int[]{4, 5, 6, 3, 2, 1};
        sort(arr);
        System.out.println(Arrays.toString(arr));
    }
}

3 插入排序

package com.xianhuii.sort;

import org.junit.Test;

import java.util.Arrays;

public class InsertSort {
    private void insert(int[] arr, int index) {
        int len = index - 1;
        int target = arr[index];
        for (int i = len; i >= 0; i--) {
            if (arr[i] > target) {
                arr[i + 1] = arr[i];
                index = i;
            } else {
                break;
            }
        }
        if (index != (len + 1)) {
            arr[index] = target;
        }
    }

    public void sort(int[] arr) {
        int len = arr.length;
        for (int i = 1; i < len; i++) {
            insert(arr, i);
        }
    }

    @Test
    public void test() {
        int[] arr = new int[]{4, 5, 6, 3, 2, 1};
        sort(arr);
        System.out.println(Arrays.toString(arr));
    }
}

4 希尔排序

package com.xianhuii.sort;

import org.junit.Test;

import java.util.Arrays;

public class ShellSort {
    private void insert(int[] arr, int index, int gap) {
        int len = index - gap;
        int target = arr[index];
        for (int i = len; i >= 0; i -= gap) {
            if (arr[i] > target) {
                arr[i + gap] = arr[i];
                index = i;
            } else {
                break;
            }
        }
        if (index != (len + gap)) {
            arr[index] = target;
        }
    }

    private void insertSort(int[] arr, int gap) {
        int len = arr.length;
        for (int i = 1; i < len; i++) {
            insert(arr, i, gap);
        }
    }

    public void sort(int[] arr) {
        int len = arr.length;
        for (int gap = len / 2; gap >= 1; gap /= 2) {
            insertSort(arr, gap);
        }
    }

    @Test
    public void test() {
        int[] arr = new int[]{8, 9, 1, 7, 6, 5, 3, 4, 2, 0};
        sort(arr);
        System.out.println(Arrays.toString(arr));
    }
}

5 快速排序

package com.xianhuii.sort;

import org.junit.Test;

import java.util.Arrays;

public class QuickSort {
    private void swap(int[] arr, int i, int j) {
        int tmp = arr[i];
        arr[i] = arr[j];
        arr[j] = tmp;
    }

    private int partition(int[] arr, int left, int right, int pivot) {
        while (left < right) {
            while (arr[left] < pivot) {
                left++;
            }
            while (arr[right] > pivot) {
                right--;
            }
            if (left < right) {
                swap(arr, left, right);
            }
        }
        return left;
    }

    private void sort(int[] arr, int left, int right) {
        if (left >= right || (left + 1 == right && arr[left] < arr[right])) {
            return;
        }
        int pivot = arr[(left + right) / 2];
        int index = partition(arr, left, right, pivot);
        sort(arr, left, index - 1);
        sort(arr, index, right);
    }

    public void sort(int[] arr) {
        sort(arr, 0, arr.length - 1);
    }

    @Test
    public void test() {
        int[] arr = new int[]{4, 3, 0, 2, 7, 1, 6, 5};
        sort(arr);
        System.out.println(Arrays.toString(arr));
    }
}

6 归并排序

package com.xianhuii.sort;

import org.junit.Test;

import java.util.Arrays;

public class MergeSort {
    private void merge(int[] arr, int left, int right) {
        int[] tmp = new int[right - left + 1];
        int index = 0;
        int mid = (left + right) >> 1;
        int l = left;
        int r = mid + 1;
        while (l <= mid && r <= right) {
            if (arr[l] < arr[r]) {
                tmp[index++] = arr[l++];
            } else {
                tmp[index++] = arr[r++];
            }
        }
        while (l <= mid) {
            tmp[index++] = arr[l++];
        }
        while (r <= right) {
            tmp[index++] = arr[r++];
        }
        index = 0;
        while (left <= right) {
            arr[left++] = tmp[index++];
        }
    }

    private void sort(int[] arr, int left, int right) {
        int mid = (left + right) >> 1;
        if (left < right) {
            sort(arr, left, mid);
            sort(arr, mid + 1, right);
            merge(arr, left, right);
        }
    }

    public void sort(int[] arr) {
        sort(arr, 0, arr.length - 1);
    }

    @Test
    public void test() {
        int[] arr = new int[]{11, 8, 3, 9, 7, 1, 2, 5};
        sort(arr);
        System.out.println(Arrays.toString(arr));
    }
}

7 基数排序

package com.xianhuii.sort;

import org.junit.Test;

import java.util.Arrays;

public class RadixSort {
    public void sort(int[] arr) {
        int length = arr.length;
        int maxIndex = 0;   // 最大值索引
        int[][] bucket = new int[10][length];   // 桶
        int[] count = new int[10];  // 记录放入个数
        int radix = 0;
        for (int i = 1; i < length; i++) {  // 寻找最大值
            if (arr[i] > arr[maxIndex]) {
                maxIndex = i;
            }
        }
        int numLen = (arr[maxIndex] + "").length(); // 求出最大值的位数
        for (int i = 0, m = 1; i < numLen; i++, m *= 10) {
            for (int j = 0; j < length; j++) {  // 按顺序入桶
                radix = arr[j] / m % 10;
                bucket[radix][count[radix]++] = arr[j];
            }
            int index = 0;
            for (int k = 0; k < bucket.length; k++) {   // 按顺序出桶
                if (count[k] != 0) {
                    for (int j = 0; j < count[k]; j++) {
                        arr[index++] = bucket[k][j];
                    }
                    count[k] = 0;
                }
            }
        }
    }

    @Test
    public void test() {
        int[] arr = new int[]{53, 542, 3, 63, 14, 214, 154, 748, 616};
        sort(arr);
        System.out.println(Arrays.toString(arr));
    }
}