【合并排序法】

/*
合并排序法 
*/ 

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define MAX1 10
#define MAX2 10

#define SWAP(x,y) {int t; t = x; x = y; y = t;} 

int partition(int[], int, int);
void quicksort(int[], int, int);
void mergesort(int[], int, int[], int, int[]);

int main(void) {
    int number1[MAX1] = {0};
    int number2[MAX1] = {0};
    int number3[MAX1+MAX2] = {0};
    int i, num;
    
    srand(time(NULL));
    printf("排序前：");
    printf("
number1[]：");
    
    for(i = 0; i < MAX1; i++) {
        number1[i] = rand() % 100;
        printf("%d ", number1[i]);
    }
    
    printf("
number2[]：");
    for(i = 0; i < MAX2; i++) {
        number2[i] = rand() % 100;
        printf("%d ", number2[i]);
    }
    // 先排序两笔资料
    quicksort(number1, 0, MAX1-1);
    quicksort(number2, 0, MAX2-1);
    
    printf("
排序后：");
    printf("
number1[]：");
    for(i = 0; i < MAX1; i++)
        printf("%d ", number1[i]);
        
    printf("
number2[]：");
    for(i = 0; i < MAX2; i++)
        printf("%d ", number2[i]);
    // 合并排序
    mergesort(number1, MAX1, number2, MAX2, number3);
    printf("
合并后：");
    for(i = 0; i < MAX1+MAX2; i++)
        printf("%d ", number3[i]); 
    printf("
");
    return 0;
}
int partition(int number[], int left, int right) {
    int i, j, s;
    s = number[right];
    i = left - 1;
    for(j = left; j < right; j++) {
        if(number[j] <= s) {
            i++;
            SWAP(number[i], number[j]);
        }
    }
    SWAP(number[i+1], number[right]);
    return i+1;
}
void quicksort(int number[], int left, int right) {
    int q;
    if(left < right) {
        q = partition(number, left, right);
        quicksort(number, left, q-1);
        quicksort(number, q+1, right);
    }
}

void mergesort(int number1[], int M, int number2[], int N, int number3[]) {
    int i = 0, j = 0, k = 0;
    while(i < M && j < N) {
        if(number1[i] <= number2[j])
            number3[k++] = number1[i++];
        else
            number3[k++] = number2[j++];
    }
    while(i < M)
        number3[k++] = number1[i++]; 
    while(j < N)
        number3[k++] = number2[j++];
}

运行结果：