- // 循环实现
- void merge(int arr[], int l, int m, int r)
- {
- int i, j, k;
- int n1 = m - l + 1;
- int n2 = r - m;
- int L[n1], R[n2];
- for (i = 0; i < n1; i++)
- L[i] = arr[l + i];
- for (j = 0; j < n2; j++)
- R[j] = arr[m + 1+ j];
- i = 0;
- j = 0;
- k = l;
- while (i < n1 && j < n2) {
- if (L[i] <= R[j]) {
- arr[k] = L[i];
- i++;
- }
- else{
- arr[k] = R[j];
- j++;
- }
- k++;
- }
- while (i < n1) {
- arr[k] = L[i];
- i++;
- k++;
- }
- while (j < n2) {
- arr[k] = R[j];
- j++;
- k++;
- }
- }
- void merge_sort(int arr[], int l, int r)
- {
- if (l < r)
- {
- int m = l+(r-l)/2;
- mergeSort(arr, l, m);
- mergeSort(arr, m+1, r);
- merge(arr, l, m, r);
- }
- }
- // 递归实现
- void merge(int arr[], int tmp[], int start, int end, int middle) {
- int l, r, s;
- s = start;
- l = start;
- r = middle + 1;
- while (l <= middle && r <= end) {
- if (arr[l] <= arr[r]) tmp[s++] = arr[l++];
- else tmp[s++] = arr[r++];
- }
- while (l <= middle) tmp[s++] = arr[l++];
- while (r <= end) tmp[s++] = arr[r++];
- for (;start <= end;start++)
- arr[start] = tmp[start];
- }
- void msort(int arr[], int *tmp, int start, int end) {
- int middle;
- if (start < end) {
- middle = (start + end) / 2;
- msort(arr, tmp, start, middle);
- msort(arr, tmp, middle + 1, end);
- merge(arr, tmp, start, end, middle);
- }
- }
- void merge_sort(int arr[], int n) {
- int *tmp = (int*)malloc(n*sizeof(int));
- msort(a, tmp, 0, n - 1);
- free(tmp);
- }
空间效率: O(n)
时间效率: 最好情况: O(Nlog2N) 平均情况: O(Nlog2N) 最坏情况: O(Nlog2N)
稳定性 (相同元素相对位置变化情况): 稳定
来源: http://www.bubuko.com/infodetail-2965688.html