链表题(leetcode)
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从头开始学习链表
链表遍历
#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.h>
#define ll long long
#define mk make_pair
#define P pair<ll,ll>
const ll N = 1e6 + 10;
const double pi = acos(-1.0);
using namespace std;
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
int main()
{
int n;
cin >> n;
ListNode *t = new ListNode(-1);
ListNode *cur = t;
for(int i=1;i<=n;i++)
{
int x;
cin >> x;
cur -> next = new ListNode(x);
cur = cur -> next;
}
cur = t -> next;
while(cur)
{
cout << cur -> val << ‘ ‘;
cur = cur -> next;
}
}
合并两个有序链表
#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.h>
#define ll long long
#define mk make_pair
#define P pair<ll,ll>
const ll N = 1e6 + 10;
const double pi = acos(-1.0);
using namespace std;
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
ListNode* merge(ListNode *l1,ListNode *l2)
{
ListNode *l3 = new ListNode(-1);
ListNode * cur = l3;
while(l1 && l2)
{
if(l1 -> val < l2 -> val)
{
cur -> next = l1;
l1 = l1 -> next;
}
else
{
cur -> next = l2;
l2 = l2 -> next;
}
cur = cur -> next;
}
if(l1)
cur -> next = l1;
else
cur -> next = l2;
return l3 -> next;
}
int main()
{
int n,m;
cin >> n >> m;
ListNode *l1 = new ListNode(-1);
ListNode *l2 = new ListNode(-1);
ListNode *cur = l1;
for(int i=1;i<=n;i++)
{
int x;
cin >> x;
cur -> next = new ListNode(x);
cur = cur -> next;
}
cur = l2;
for(int i=1;i<=m;i++)
{
int x;
cin >> x;
cur -> next = new ListNode(x);
cur = cur -> next;
}
ListNode *l3 = merge(l1->next,l2->next);
cur = l3;
while(cur)
{
cout << cur->val << ‘ ‘;
cur = cur -> next;
}
return 0;
}
链表相加
#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.h>
#define ll long long
#define mk make_pair
#define P pair<ll,ll>
const ll N = 1e6 + 10;
const double pi = acos(-1.0);
using namespace std;
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
ListNode* add(ListNode *l1,ListNode *l2)
{
ListNode *l3 = new ListNode(-1);
ListNode * cur = l3;
int t = 0;
while(l1 || l2)
{
int x1 = 0,x2 = 0;
if(l1)
x1 = l1 -> val;
if(l2)
x2 = l2 -> val;
int tt = x1 + x2 + t;
cur -> next = new ListNode(tt%10);
t = tt / 10;
cur = cur -> next;
if(l1)
l1 = l1 -> next;
if(l2)
l2 = l2 -> next;
}
if(t)
cur -> next = new ListNode(t);
return l3 -> next;
}
int main()
{
int n,m;
cin >> n >> m;
ListNode *l1 = new ListNode(-1);
ListNode *l2 = new ListNode(-1);
ListNode *cur = l1;
for(int i=1;i<=n;i++)
{
int x;
cin >> x;
cur -> next = new ListNode(x);
cur = cur -> next;
}
cur = l2;
for(int i=1;i<=m;i++)
{
int x;
cin >> x;
cur -> next = new ListNode(x);
cur = cur -> next;
}
ListNode *l3 = add(l1->next,l2->next);
cur = l3;
while(cur)
{
cout << cur->val << ‘ ‘;
cur = cur -> next;
}
return 0;
}
排序链表
#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.h>
#define ll long long
#define mk make_pair
#define P pair<ll,ll>
const ll N = 1e6 + 10;
const double pi = acos(-1.0);
using namespace std;
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
ListNode* merge(ListNode *l1,ListNode *l2)
{
ListNode *l3 = new ListNode(-1);
ListNode * cur = l3;
while(l1 && l2)
{
if(l1 -> val < l2 -> val)
{
cur -> next = l1;
l1 = l1 -> next;
}
else
{
cur -> next = l2;
l2 = l2 -> next;
}
cur = cur -> next;
}
if(l1)
cur -> next = l1;
else
cur -> next = l2;
return l3 -> next;
}
ListNode* sort(ListNode *head)
{
if(!head || !head->next)
return head;
ListNode *fast = head,*slow = head,*mid = head;
while(fast)// 1 2 3
{
mid = slow;
slow = slow -> next;
if(fast->next)
fast = fast -> next -> next;
else
break;
}
mid -> next = NULL;
return merge(sort(head),sort(slow));
}
int main()
{
int n;
cin >> n;
ListNode *l1 = new ListNode(-1);
ListNode *cur = l1;
for(int i=1;i<=n;i++)
{
int x;
cin >> x;
cur -> next = new ListNode(x);
cur = cur -> next;
}
ListNode* l2 = sort(l1->next);
cur = l2;
while(cur)
{
cout << cur->val << ‘ ‘;
cur = cur -> next;
}
return 0;
}
合并k个排序链表
#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.h>
#define ll long long
#define mk make_pair
#define P pair<ll,ll>
const ll N = 1e6 + 10;
const double pi = acos(-1.0);
using namespace std;
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
ListNode* mergeTwoListNode(ListNode *l1,ListNode *l2)
{
ListNode *l3 = new ListNode(-1);
ListNode * cur = l3;
while(l1 && l2)
{
if(l1 -> val < l2 -> val)
{
cur -> next = l1;
l1 = l1 -> next;
}
else
{
cur -> next = l2;
l2 = l2 -> next;
}
cur = cur -> next;
}
if(l1)
cur -> next = l1;
else
cur -> next = l2;
return l3 -> next;
}
ListNode *merge(vector<ListNode*>lists,int left,int right)
{
if(left == right)
return lists[left];
int mid = (left + right) / 2;
ListNode *l1 = merge(lists,left,mid);
ListNode *l2 = merge(lists,mid+1,right);
return mergeTwoListNode(l1,l2);
}
ListNode* mergeKLists(vector<ListNode*>& lists)
{
int k = lists.size();
ListNode *head = new ListNode(-1);
return merge(lists,0,k-1);
}
int main()
{
int n,k,x;
cin >> k;
vector<ListNode*> v;
for(int i=1;i<=k;i++)
{
cin >> n;
ListNode *head = new ListNode(-1); ListNode *cur = head;
for(int j=1;j<=n;j++)
{
cin >> x;
cur->next = new ListNode(x);
cur = cur -> next;
}
v.push_back(head->next);
}
// ListNode *cur = new ListNode(-1);
// cur->next = v[0];
// while(cur)
// {
// cout << cur -> val;
// cur = cur -> next;
// }
ListNode *l1 = mergeKLists(v);
while(l1)
{
cout << l1 -> val << ‘ ‘;
l1 = l1 -> next;
}
return 0;
}
/*
3
3 1 2 3
2 1 2
1 1
1
3 3 2 1
*/
删除链表倒数第k个节点
#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.h>
#define ll long long
#define mk make_pair
#define P pair<ll,ll>
const ll N = 1e6 + 10;
const double pi = acos(-1.0);
using namespace std;
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
ListNode* eraseListNodeKth(ListNode *head,int k)
{
ListNode *cur = head;
int len = 0;
while(cur)
{
cur = cur -> next;
len++;
}
ListNode *ans = new ListNode(-1);
ListNode *cur1 = head;
cur = ans;
for(int i=0;i<len;i++)
{
if(i==len-k)
{
cur1 = cur1 -> next;
}
if(!cur1)
break;
cur -> next = new ListNode(cur1->val);
cur = cur -> next;
cur1 = cur1 -> next;
}
return ans->next;
}
int main()
{
int n,x,k;
cin >> n >> k;
ListNode* head = new ListNode(-1);
ListNode* cur = head;
for(int i=1;i<=n;i++)
{
cin >> x;
cur -> next = new ListNode(x);
cur = cur -> next;
}
ListNode* ans = eraseListNodeKth(head->next,k);
while(ans)
{
cout << ans -> val << ‘ ‘;
ans = ans -> next;
}
return 0;
}
链表反转
#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.h>
#define ll long long
#define mk make_pair
#define P pair<ll,ll>
const ll N = 1e6 + 10;
const double pi = acos(-1.0);
using namespace std;
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
ListNode* reverseList(ListNode *head)
{
ListNode *cur = NULL;
ListNode *pre = head;
while(pre)
{
ListNode *t = pre -> next;
pre -> next = cur;
cur = pre;
pre = t;
}
return cur;
}
int main()
{
int n,x,k;
cin >> n;
ListNode* head = new ListNode(-1);
ListNode* cur = head;
for(int i=1;i<=n;i++)
{
cin >> x;
cur -> next = new ListNode(x);
cur = cur -> next;
}
ListNode* ans = reverseList(head->next);
while(ans)
{
cout << ans -> val << ‘ ‘;
ans = ans -> next;
}
return 0;
}
链表去重
#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.h>
#define ll long long
#define mk make_pair
#define P pair<ll,ll>
const ll N = 1e6 + 10;
const double pi = acos(-1.0);
using namespace std;
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
void deleteDuplicates(ListNode* head) {
ListNode *cur = head;
while(cur)
{
while(cur->next && cur->val == cur->next->val)
{
cur ->next = cur -> next -> next;
}
cur = cur -> next;
}
}
int main()
{
int n,x,k;
cin >> n;
ListNode* head = new ListNode(-1);
ListNode* cur = head;
for(int i=1;i<=n;i++)
{
cin >> x;
cur -> next = new ListNode(x);
cur = cur -> next;
}
deleteDuplicates(head->next);
cur = head -> next;
while(cur)
{
cout << cur -> val << ‘ ‘;
cur = cur -> next;
}
return 0;
}
交换链表两个节点
#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.h>
#define ll long long
#define mk make_pair
#define P pair<ll,ll>
const ll N = 1e6 + 10;
const double pi = acos(-1.0);
using namespace std;
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
ListNode* swap2(ListNode *head)
{
if(!head || !head -> next)
return head;
ListNode *ans = new ListNode(-1);
ans ->next = head;
ListNode *cur = ans;
while(cur -> next&& cur -> next->next) {
ListNode *now = cur->next, *nxt = cur->next->next, *t = nxt->next;
nxt->next = now;
cur -> next = nxt;
now->next = t;
cur = now;
}
return ans -> next;
}
//-1 -> 1 -> 2 -> 3 -> 4 -> 5
// -1 -> 2 -> 1 -> 3 <- 4 5
int main()
{
int n,x;
cin >> n;
ListNode *head = new ListNode(-1);
ListNode *cur = head;
for(int i=1;i<=n;i++)
{
cin >> x;
cur -> next = new ListNode(x);
cur = cur -> next;
}
cur = swap2(head -> next);
while(cur)
{
cout << cur -> val << ‘ ‘;
cur = cur -> next;
}
return 0;
}
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