leetcode

Solution to some Leetcode problems written in C++
git clone git://git.dimitrijedobrota.com/leetcode.git
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commit4d3e1fb637c5d4393166c54b2abcd30521d4c61e
parent6b97a182ad0c8a154b8d9635927778ce6cf328c7
authorDimitrije Dobrota <mail@dimitrijedobrota.com>
dateSun, 12 Mar 2023 19:14:23 +0100

Daily Problem

Diffstat:
MProblems/0023.cpp|++++++++++++++++++++++++++

1 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/Problems/0023.cpp b/Problems/0023.cpp

@@ -1,3 +1,4 @@

// Naive solution, barely passed
class Solution {
public:
ListNode *mergeKLists(vector<ListNode *> &lists) {

@@ -20,3 +21,28 @@ public:

return dummy->next;
}
};
// Proper solution
class Solution {
typedef pair<int, int> pii;
public:
ListNode *mergeKLists(vector<ListNode *> &lists) {
ListNode *dummy, *tmp;
tmp = dummy = new ListNode;
auto cmp = [](const pii &a, const pii &b) { return a.first > b.first; };
priority_queue<pii, vector<pii>, decltype(cmp)> pq(cmp);
for (int i = 0; i < lists.size(); i++)
if (lists[i]) pq.push({lists[i]->val, i});
while (!pq.empty()) {
int index = pq.top().second;
pq.pop();
ListNode *t = lists[index];
lists[index] = lists[index]->next;
if (lists[index]) pq.push({lists[index]->val, index});
tmp = tmp->next = t;
}
return dummy->next;
}
};