选择排序

  1. public class P {
  2.   public static void selectionSort(int[] arr) {
  3.     for (int i = 0; i < arr.length - 1; ++i) {
  4.       int temp = arr[i];
  5.       int flag = i;
  6.       for (int j = i + 1; j < arr.length; ++j) {
  7.         if (arr[j] < temp) {
  8.           temp = arr[j];
  9.           flag = j;
  10.         }
  11.       }
  12.       if (i != flag) {
  13.         arr[flag] = arr[i];
  14.         arr[i] = temp;
  15.       }
  16.     }
  17.   }
  19.   public static void main(String[] args) {
  20.     int[] arr = {2, 5, 7, 2, 1};
  21.     P.selectionSort(arr);
  22.     for (int a : arr) {
  23.       System.out.println(a);
  24.     }
  25.   }
  26. }

插入排序

  1. public class P {
  2.   public static void insertSort(int[] arr) {
  3.     int temp;
  4.     int h;
  5.     for (int i = 1; i < arr.length; ++i) {
  6.       temp = arr[i];
  7.       if (arr[i] < arr[i - 1]) {
  8.         for (h = i - 1; h >= 0 && temp < arr[h]; --h) {
  9.           arr[h + 1] = arr[h];
  10.         }
  11.         arr[h + 1] = temp;
  12.       }
  13.     }
  14.   }
  16.   public static void main(String[] args) {
  17.     int[] arr = {2, 5, 7, 2, 1};
  18.     P.insertSort(arr);
  19.     for (int a : arr) {
  20.       System.out.println(a);
  21.     }
  22.   }
  23. }

希尔排序

  1. import java.util.Arrays;
  3. public class P {
  4.   public static void main(String[] args) {
  5.     int[] arr = {1, 2, 3, 5, 1, 2};
  6.     shellSort(arr);
  7.     System.out.println(Arrays.toString(arr));
  8.   }
  10.   public static void shellSort(int[] arr) {
  11.     int temp;
  12.     for (int gap = arr.length / 2; gap >= 1; gap /= 2) {
  13.       for (int i = gap; i < arr.length; ++i) {
  14.         for (int j = i - gap; j >= 0; j -= gap) {
  15.           if (arr[j] > arr[j + gap]) {
  16.             temp = arr[j + gap];
  17.             arr[j + gap] = arr[j];
  18.             arr[j] = temp;
  19.           }
  20.         }
  21.       }
  22.     }
  23.   }
  24. }

归并排序

  1. public class Sort {
  2.   public static void merge(int[] a, int lo, int mid, int hi) {
  3.     int i = lo, j = mid + 1;
  4.     int[] aux = new int[hi + 1];
  5.     for (int k = lo; k <= hi; ++k) {
  6.       aux[k] = a[k];
  7.     }
  8.     for (int k = lo; k <= hi; ++k) {
  9.       if (i > mid) {
  10.         a[k] = aux[j++];
  11.       } else if (j > hi) {
  12.         a[k] = aux[i++];
  13.       } else if (aux[j] < aux[i]) {
  14.         a[k] = aux[j++];
  15.       } else {
  16.         a[k] = aux[i++];
  17.       }
  18.     }
  19.   }
  20. }