[LeetCode] Add January 24.

pin3da · Jan 24, 2021 · 08ac8bd · 08ac8bd
1 parent eb63346
commit 08ac8bd
Showing 1 changed file with 42 additions and 0 deletions.
diff --git a/solved/LeetCode/Challenges/2020/January/24.cc b/solved/LeetCode/Challenges/2020/January/24.cc
@@ -0,0 +1,42 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+struct ListNode {
+  int val;
+  ListNode *next;
+  ListNode() : val(0), next(nullptr) {}
+  ListNode(int x) : val(x), next(nullptr) {}
+  ListNode(int x, ListNode *next) : val(x), next(next) {}
+};
+
+class Solution {
+ public:
+  ListNode* mergeKLists(vector<ListNode*>& lists) {
+    set<pair<int, ListNode*>> bestList;
+    for (auto it : lists) {
+      if (it != nullptr) {
+        bestList.insert(make_pair(it->val, it));
+      }
+    }
+
+    ListNode* head = nullptr;
+    ListNode* cur = nullptr;
+    while (bestList.size() > 0) {
+      ListNode* first = bestList.begin()->second;
+      ListNode* next = first->next;
+      bestList.erase(bestList.begin());
+      if (head == nullptr) {
+        head = first;
+        cur = first;
+      } else {
+        cur->next = first;
+        cur = first;
+      }
+      if (next != nullptr) {
+        bestList.insert(make_pair(next->val, next));
+      }
+    }
+    return head;
+  }
+};