算法之排序:归并
//归并 public static void sort4(int[] arr) { if (arr == null || arr.length < 2) { return; } sortProcess(arr, 0, arr.length - 1); } public static void sortProcess(int[] arr, int l, int r) { if (l == r) { return; } int mid = (l + r) / 2; sortProcess(arr, l, mid); sortProcess(arr, mid + 1, r); merge(arr, l, mid, r); } public static void merge(int[] arr, int l, int mid, int r) { int arr2[] = new int[r - l + 1]; int i = 0; int p1 = l; int p2 = mid + 1; while (p1 <= mid && p2 <= r) { if (arr[p1] <= arr[p2]) { arr2[i++] = arr[p1++]; } else { arr2[i++] = arr[p2++]; } } if (p1 > mid) { while (p2 <= r) { arr2[i++] = arr[p2++]; } } else if (p2 > r) { while (p1 <= mid) { arr2[i++] = arr[p1++]; } } for (i = 0; i < arr2.length; i++) { arr[l + i] = arr2[i]; } }