2017-09-11 LeetCode_023 Merge k Sorted Lists

23. Merge k Sorted Lists

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.
solution:

class Solution {

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public:

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   ListNode* mergeKLists(vector<ListNode*>& lists) {

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       int min = INT_MAX, d = -1;

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for (int i = 0; i < lists.size(); i++)

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if (lists[i] != NULL && lists[i]->val <= min) {

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min = lists[i]->val; d = i;

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}

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if (d == -1) return NULL;

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ListNode *p = lists[d];

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lists[d] = lists[d]->next;

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p->next = mergeKLists(lists);

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return p;

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   }

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};