66 lines
1.4 KiB
C++
66 lines
1.4 KiB
C++
#include <queue>
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#include <vector>
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#include <iostream>
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struct ListNode {
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int val;
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ListNode* next;
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explicit ListNode(int x = 0, ListNode* next = nullptr) : val(x), next(next) {}
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};
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ListNode* construct(int x) {
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return new ListNode(x);
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}
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template<typename... Ts>
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ListNode* construct(int x, Ts... xs) {
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return new ListNode(x, construct(xs...));
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}
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struct cmp {
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bool operator()(const ListNode* x, const ListNode* y) {
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return x && (!y || x->val > y->val);
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}
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};
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/**
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* 23. Merge k Sorted Lists
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*
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* You are given an array of k linked-lists lists, each linked-list is sorted in ascending order.
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* Merge all the linked-lists into one sorted linked-list and return it.
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*/
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class Solution {
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public:
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static ListNode* mergeKLists(const std::vector<ListNode*>& lists) {
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if (lists.empty())
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return nullptr;
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std::priority_queue<ListNode*, std::vector<ListNode*>, cmp> q(lists.begin(), lists.end());
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ListNode* ptr = new ListNode(0), * head = ptr;
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for (; !q.empty() && !q.top(); q.pop());
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while (!q.empty()) {
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ListNode* p = q.top();
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q.pop();
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ptr = ptr->next = new ListNode(p->val);
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if (p->next)
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q.push(p->next);
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}
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return head->next;
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}
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};
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int main() {
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ListNode* h = Solution::mergeKLists({
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construct(1, 4, 5),
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nullptr,
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construct(1, 3, 4),
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construct(2, 6),
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nullptr,
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nullptr
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});
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for (ListNode* ptr = h; ptr; ptr = ptr->next)
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std::cout << ptr->val << "\n";
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return 0;
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}
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