【IT笔试面试题整理】反转链表

【试题描述】定义一个函数,输入一个链表的头节点,反转该链表并输出反转后链表的头节点

【试题来源】未知

【参考代码】

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#include <iostream>
using namespace std;

struct ListNode {
int value;
ListNode* next;
};

ListNode* createList(int* data, int n) {

ListNode* headNode = NULL;
ListNode* lastNode = NULL;

for(int i = 0; i < n; i++) {
ListNode* node = new ListNode();
node->value = data[i];
node->next = NULL;
if(i == 0) {
headNode = node;
} else {
lastNode->next = node;
}
lastNode = node;
}

return headNode;
}

void printList(ListNode* headNode) {

if(headNode == NULL) {
return ;
}
ListNode* node = headNode;
while(node != NULL) {
cout << node->value << " ";
node = node->next;
}
}

ListNode* reverseList(ListNode* headNode) {

if(headNode == NULL) {
return NULL;
}

ListNode* curNode = headNode;
ListNode* preNode = NULL;
ListNode* nextNode = NULL;

while(curNode != NULL) {

nextNode = curNode->next;
curNode->next = preNode;
preNode = curNode;
curNode = nextNode;

}
return preNode;
}

int main() {
int data[] = {1, 2, 3, 4, 5, 6, 7};
int n = 7;
ListNode* headNode = createList(data, n);
ListNode* reverseNode = reverseList(headNode);
printList(reverseNode);
return 0;
}
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