归并排序算法个人理解

来源：互联网发布：网络公关公司危机公关编辑：程序博客网时间：2024/06/16 11:53

如果把排序当作层次不齐的线条归并排序和二分法很像不断的递归完成分割直到元素个数为1假设元素个数1有序再和他右边的伙伴比较合并所以合并的次数 logN 最终合并完成的数再排序N次复杂度为N*(logN) 如图分割

#include <stdio.h>#include <stdlib.h>void Merge(int array[], int start, int middle, int end){int i, j, k, n1, n2;n1 = middle - start + 1;              n2 = end - middle; int *L = (int *)malloc(n1 * sizeof(int));int *R = (int *)malloc(n2 * sizeof(int));for (i = 0, k = start; i < n1; i++, k++){L[i] = array[k];//左端取值 }for (i = 0, k = middle + 1; i < n2; i++, k++){R[i] = array[k];//右端取值 }for (k = start, i = 0, j = 0; i < n1 && j < n2; k++){if (L[i] < R[j]){array[k] = L[i];i++;}else{array[k] = R[j];j++;}}//比较插入 if (i < n1){for (j = i; j < n1; j++, k++){array[k] = L[j];}}if (j < n2){for (i = j; i < n2; i++, k++){array[k] = R[i];}}//合并过程 }void MergeSort(int array[], int start, int end){int middle;int i;if (start < end){middle = (start + end) / 2;MergeSort(array, start, middle);MergeSort(array, middle + 1, end);Merge(array, start, middle, end);}}int main(){int i = 0;int a[] = {49, 38, 65, 97, 76, 13, 27};int length = sizeof(a) / sizeof(a[0]);MergeSort(a, 0, length -1);for (i = 0 ; i < length; i++){printf("%d ", a[i]);}printf("\n");return 0;}

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