LeetCode 143 Reorder List

原创

wx634e39bb59725 2022-10-18 13:53:44 博主文章分类：每周算法练习 ©著作权

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这道题目我真是无语。

不知道判题程序是怎么判断TLE的。
下面我贴出我的测试程序，两个解决方案，经过10次测试，消耗的时间.
方案1 是TLE的方案，方案2 是AC的方案

代码

//
//  main.cpp
//  test
//
//  Created by 小康 on 20/11/2018.
//  Copyright © 2018 小康. All rights reserved.
//

#include <iostream>
using namespace std;
struct ListNode {
         int val;
         ListNode *next;
         ListNode(int x) : val(x), next(NULL) {}
    };

class Solution {
public:
    ListNode* a[100005];
    void reorderList(ListNode* head) {
        if(head ==NULL ||head->next==NULL) return;
        ListNode* iter = head;
        ListNode* iter2 = head;
        int tag=0;
        ListNode* term;
        int pos =0;
        while(iter2&&iter2->next)
        {
            a[tag++]=iter;
            iter=iter->next;
            iter2 = iter2->next->next;
        }
        if(iter2)
            term = a[tag-1]->next->next;
        else
            term = a[tag-1]->next;
        
        ListNode* temp;
        
        for(int i=tag-1;i>=0;i--)
        {
            temp = term;
            term = term->next;
            temp->next=a[i]->next;
            a[i]->next = temp;
        }
    }
};

class Solution2 {
public:
    ListNode* a[100005];
    void reorderList(ListNode* head) {
        if(head ==NULL ||head->next==NULL) return;
        ListNode* iter = head;
        ListNode* iter2 = head;
        int tag=0;
        ListNode* term;
        int pos =0;
        while(iter2&&iter2->next)
        {
            a[tag++]=iter;
            iter=iter->next;
            iter2 = iter2->next->next;
        }
        term = a[tag-1]->next;
        if(iter2==NULL)  tag--;
        
        ListNode* temp;
        for(int i=tag-1;i>=0;i--)
        {
            temp = term->next;
            term->next = temp->next;
            temp->next =a[i]->next;
            a[i]->next = temp;
            
        }
        
        
    }
};
int main() {
   
    clock_t start,end;
    
  
    int i=0;
    while(i<10){
        cout<<i<<endl;
       start = clock();
    ListNode* head = new ListNode(1);
    head->next = new ListNode(2);
    head->next->next = new ListNode(3);
    head->next->next->next = new ListNode(4);
    Solution* s = new Solution();
    s->reorderList(head);
     end = clock();
    
    double dur = (double)(end - start);
    printf("Use Time1 :%f   ",dur);
    
    start = clock();
    ListNode* head2 = new ListNode(1);
    head2->next = new ListNode(2);
    head2->next->next = new ListNode(3);
    head2->next->next->next = new ListNode(4);
    Solution2* s2 = new Solution2();
    s2->reorderList(head2);
     end = clock();
    double dur2 = (double)(end - start);
    printf("Use Time2 :%f\n",dur2);
        i++;
    }
  
  
}

测试结果：

0
Use Time1 :368.000000   Use Time2 :367.000000
1
Use Time1 :396.000000   Use Time2 :337.000000
2
Use Time1 :405.000000   Use Time2 :386.000000
3
Use Time1 :339.000000   Use Time2 :405.000000
4
Use Time1 :363.000000   Use Time2 :383.000000
5
Use Time1 :351.000000   Use Time2 :371.000000
6
Use Time1 :332.000000   Use Time2 :335.000000
7
Use Time1 :388.000000   Use Time2 :345.000000
8
Use Time1 :361.000000   Use Time2 :367.000000
9
Use Time1 :347.000000   Use Time2 :372.000000
Program ended with exit code: 0