有序表的合并

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本文链接： https://blog.csdn.net/qq_37245458/article/details/89019838

问题描述：将两个有序表合并。例如 l1={1，2，3，4，5}，l2={2，3，4，5，6} =>l3={1，2，2，3，3，4，4，5，5，6}。

分析：将两个有序表合并，就是归并的过程。

解题思路：实现归并排序的归并过程即可。

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

#include <iostream>
#include <string>
#include <vector>
using namespace std;

struct List {
	int data;
	struct List* next;
};
typedef List* ListPtr;

void 
create_list(ListPtr* list_node, int data) {
	ListPtr refer_ptr = (ListPtr)malloc(sizeof(struct List));
	refer_ptr->data = data;
	refer_ptr->next = NULL;

	*list_node = refer_ptr;
}

void 
insert_node(ListPtr* list_node, struct List* node) {
	struct List** refer_ptr = list_node;

	while (*refer_ptr)
		refer_ptr = &(*refer_ptr)->next;

	*refer_ptr = node;
	node->next = NULL;
}

void
sort_list_node(ListPtr l1, ListPtr l2, ListPtr* l3) {
	if (l1 == NULL || l2 == NULL)
		return;

	struct List** refer_l3_ptr = l3;
	while (l1 && l2) {
		if (l1->data < l2->data) {
			*refer_l3_ptr = l1;
			l1 = l1->next;
			refer_l3_ptr = &(*refer_l3_ptr)->next;
		}	
		else {
			*refer_l3_ptr = l2;
			l2 = l2->next;
			refer_l3_ptr = &(*refer_l3_ptr)->next;
		}
	}
	while (l1) {
		*refer_l3_ptr = l1;
		l1 = l1->next;
		refer_l3_ptr = &(*refer_l3_ptr)->next;
	}
	while (l2) {
		*refer_l3_ptr = l2;
		l2 = l2->next;
		refer_l3_ptr = &(*refer_l3_ptr)->next;
	}
}

void
print_list(ListPtr* list) {
	struct List** refer_ptr = list;

	while (*refer_ptr) {
		cout << (*refer_ptr)->data << " ";
		refer_ptr = &(*refer_ptr)->next;
	}
	cout << endl;
}

int main(int argc, char** argv) {
	struct List* l1 = NULL;
	struct List* l2 = NULL;

	int data = 0;
	cin >> data;
	create_list(&l1, data);

	while (getchar() == ' ') {
		cin >> data;
		struct List* node = (struct List*)malloc(sizeof(struct List));
		node->data = data;
		insert_node(&l1, node);
	}

	cin >> data;
	create_list(&l2, data);

	while (getchar() == ' ') {
		cin >> data;
		struct List* node = (struct List*)malloc(sizeof(struct List));
		node->data = data;
		insert_node(&l2, node);
	}

	struct List* l3 = NULL;
	sort_list_node(l1, l2, &l3);
	print_list(&l3);

	system("pause");
	return 0;
}