K路归并排序问题的C语言实现
时间: 2023-10-17 15:17:40 浏览: 42
归并排序是一种基于分治思想的排序算法,在K路归并排序中,将数组分成K组,每一组进行归并排序,最后将K个有序数组合并成一个有序数组。以下是K路归并排序的C语言实现:
```c
#include <stdio.h>
#include <stdlib.h>
// 归并函数
void merge(int *arr, int start, int mid, int end) {
int len1 = mid - start + 1;
int len2 = end - mid;
int *temp1 = (int*)malloc(sizeof(int)*len1);
int *temp2 = (int*)malloc(sizeof(int)*len2);
int i, j, k;
for (i = 0; i < len1; i++) {
temp1[i] = arr[start + i];
}
for (j = 0; j < len2; j++) {
temp2[j] = arr[mid + 1 + j];
}
i = j = 0;
k = start;
while (i < len1 && j < len2) {
if (temp1[i] <= temp2[j]) {
arr[k++] = temp1[i++];
}
else {
arr[k++] = temp2[j++];
}
}
while (i < len1) {
arr[k++] = temp1[i++];
}
while (j < len2) {
arr[k++] = temp2[j++];
}
free(temp1);
free(temp2);
}
// K路归并函数
void merge_k(int *arr[], int n, int k, int *result) {
int i, j, start, end, mid;
int *pos = (int*)malloc(sizeof(int)*k);
for (i = 0; i < k; i++) {
pos[i] = 0;
}
for (i = 0; i < n; i++) {
result[i] = arr[i][0];
}
for (i = 0; i < n*k; i++) {
int min = result[0], min_index = 0;
for (j = 1; j < n; j++) {
if (pos[j] < k && result[j*k+pos[j]] < min) {
min = result[j*k+pos[j]];
min_index = j;
}
}
if (min_index == 0) {
start = 0;
}
else {
start = min_index*k+pos[min_index];
}
end = (min_index+1)*k-1;
if (end >= n*k) {
end = n*k-1;
}
mid = (start + end) / 2;
merge(result, start, mid, end);
pos[min_index]++;
}
free(pos);
}
int main() {
int n, k, i, j;
printf("请输入数组个数n和每个数组的元素个数k:");
scanf("%d %d", &n, &k);
int **arr = (int**)malloc(sizeof(int*)*n);
int *result = (int*)malloc(sizeof(int)*n*k);
for (i = 0; i < n; i++) {
arr[i] = (int*)malloc(sizeof(int)*k);
printf("请输入第%d个数组:", i+1);
for (j = 0; j < k; j++) {
scanf("%d", &arr[i][j]);
}
}
merge_k(arr, n, k, result);
printf("排序后的结果为:");
for (i = 0; i < n*k; i++) {
printf("%d ", result[i]);
}
printf("\n");
free(result);
for (i = 0; i < n; i++) {
free(arr[i]);
}
free(arr);
return 0;
}
```
以上代码实现了K路归并排序的基本思想,通过归并排序将K个数组分别排序后再进行合并。程序中通过一个pos数组来记录每个数组中已经处理的元素个数,每次选择K个数组中最小的元素进行合并,合并结束后更新pos数组。