java常用排序演算法

氣泡排序

public static void bubble(int[] arr) {
        int tem;
        for (int i = 1; i < arr.length; ++i) {
            // 負輔助變數，用於提前結束
            int count = 0;
            for (int j = 1; j < arr.length; ++j) {
                if (arr[j - 1] > arr[j]) {
                    tem = arr[j];
                    arr[j] = arr[j - 1];
                    arr[j - 1] = tem;
                    // 減少賦值判斷
                    if (count == 0) {
                        ++count;
                    }
                }
            }
            if (count == 0) {
                break;
            }
        }
    }
 

選擇排序

public static void select(int[] arr) {
    for (int i = 0; i < arr.length - 1; ++i) {
        // 找到最小值和下標
        int minIndex = i;
        int min = arr[i];
        for (int j = i + 1; j < arr.length; ++j) {
            if (min > arr[j]) {
                min = arr[j];
                minIndex = j;
            }
        }
        // 交換
        if (minIndex != i) {
            arr[minIndex] = arr[i];
            arr[i] = min;
        }
    }
}
 

插入排序

public static void insert(int[] arr) {
    for (int i = 1; i < arr.length; ++i) {

        int insertValue = arr[i];
        int insertIndex = i - 1;

        while (insertIndex >= 0 && insertValue < arr[insertIndex]) {
            arr[insertIndex + 1] = arr[insertIndex];
            --insertIndex;
        }
        arr[insertIndex + 1] = insertValue;
    }
}
 

希爾排序

交換法

public static void shell01(int[] arr) {
    int temp;
    for (int gap = arr.length / 2; gap > 0; gap /= 2) {
        for (int i = gap; i < arr.length; ++i) {
            for (int j = i - gap; j >= 0; j -= gap) {
                if (arr[j] > arr[j + gap]) {
                    temp = arr[j];
                    arr[j] = arr[j + gap];
                    arr[j + gap] = temp;
                }
            }
        }
    }
}

位移法

public static void shell02(int[] arr) {
        for (int gap = arr.length / 2; gap > 0; gap /= 2) {
            for (int i = gap; i < arr.length; ++i) {
                // 儲存下標和值
                int index = i;
                int temp = arr[index];
                while (index - gap >= 0 && temp < arr[index - gap]) {
                    // 移動
                    arr[index] = arr[index - gap];
                    index -= gap;
                }
                arr[index] = temp;

            }
        }
    }