c_cpp FP风格的反向单链表

Posted 2021-05-14

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

typedef struct SinglyLinkedListNode {
	int value;
	struct SinglyLinkedListNode* next;
} SinglyLinkedListNode;

SinglyLinkedListNode* reverseSinglyLinkedList(SinglyLinkedListNode* list);
SinglyLinkedListNode* reverseSinglyLinkedListHelper(SinglyLinkedListNode* listToReverse, SinglyLinkedListNode* listToAppend);

SinglyLinkedListNode* reverseSinglyLinkedList(SinglyLinkedListNode* list) {
	return reverseSinglyLinkedListHelper(list, NULL);
}

SinglyLinkedListNode* reverseSinglyLinkedListHelper(SinglyLinkedListNode* listToReverse, SinglyLinkedListNode* listToAppend) {
	if (listToReverse == NULL) {
		return listToAppend;
	}
	else {
		SinglyLinkedListNode* firstToReverse = listToReverse;
		SinglyLinkedListNode* restToReverse = firstToReverse->next;
		firstToReverse->next = listToAppend;
		return reverseSinglyLinkedListHelper(restToReverse, firstToReverse);
	}
}

int main() {
	SinglyLinkedListNode* singlyLinkedList = NULL;

	for (int i = 0; i < 5; i++) {
		SinglyLinkedListNode* newNode = (SinglyLinkedListNode*)malloc(sizeof(SinglyLinkedListNode));
		newNode->value = i;
		newNode->next = singlyLinkedList;
		singlyLinkedList = newNode;
	}

	singlyLinkedList = reverseSinglyLinkedList(singlyLinkedList);

	SinglyLinkedListNode* currNode = singlyLinkedList;
	for (int i = 0; i < 5; i++) {
		if (currNode->value != i) {
			printf("error\n");
		}
		currNode = currNode->next;
	}

	return 0;
}