move_zero(linklist version)

题目：Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements.

For example, given nums = [0, 1, 0, 3, 12], after calling your function, nums should be [1, 3, 12, 0, 0].

解答：用linklist来做，用两个头指针来指向0开头和不是0开头的链表，最后连起来。

#include <iostream>

using namespace  std;

/**
 * Definition for singly-linked list.*/
struct ListNode {
    int val;
    ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};

ListNode* init(int a[], int n){
    ListNode* q = NULL, *head = NULL;
    for(int i = 0; i < n; i++){
        ListNode* p = new ListNode(0);
        p->val = a[i];
        if(i==0){//不要忽略头结点的赋值
            head = q = p;
            continue;
        }
        q->next=p;
        q = q->next;
    }
    q->next = NULL;
    return  head;
    
}


ListNode* move_zero(ListNode* head){
    ListNode* p = head, *q = head, *r = head, *s = head;//p denote the moving point, r is the head of zero
    bool zero = false; //用bool标记是否是开头，我觉得挺好用的
    bool h = false;
    while(p != NULL){
        if(p->val == 0){
            if(zero == false){
                r = p;
                s = r;
                zero = true;
            }else{
                s->next = p;
                s = s->next;
            }
            
        }else{
            if(h == false){
                head = p;
                q = p;
                h = true;
            }else{
                q->next = p;
                q = q->next;
            }
        
        }
        p = p->next;
    }
    q->next = r;
    s->next = NULL;
    return head;
}

void prints(ListNode* head){
    while(head){
        cout<<head->val<<" ";
        head = head->next;
    }
}





int main(int argc, const char * argv[]) {
    //int a[]={2,5,3,7,9,4,1,8};
    int a[]={0, 1, 0, 3,12};
    ListNode* head =new ListNode(0);
    head=init(a,5);
    ListNode* L = move_zero(head);
    prints(L);
    return 0;
}

测试用例：

输入：

0, 1, 0, 3, 12

输出：

1 3 12 0 0

2.数组版本

这里用他人更简短的代码

    void moveZeroes(vector<int>& nums) {
        int j = 0;
    for(int i = 0; i < nums.size(); i++) {
        if(nums[i] != 0) {
            int temp = nums[j];
            nums[j] = nums[i];
            nums[i] = temp;
            j++;
        }
    }
    }