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Commit 2847082

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solve problem Kth Largest Element In An Array
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‎README.md

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|394|[Decode String](https://leetcode-cn.com/problems/decode-string/description/)|[java/py/js](./algorithms/DecodeString)|Medium|
314314
|938|[Range Sum Of Bst](https://leetcode-cn.com/problems/range-sum-of-bst/description/)|[java/py/js](./algorithms/RangeSumOfBst)|Medium|
315315
|71|[Simplify Path](https://leetcode-cn.com/problems/simplify-path/description/)|[java/py/js](./algorithms/SimplifyPath)|Medium|
316-
|451|[Sort Characters By Frequency](https://leetcode-cn.com/problems/sort-characters-by-frequency/description/)|[java/py/js](./SortCharactersByFrequency)|Medium|
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|451|[Sort Characters By Frequency](https://leetcode-cn.com/problems/sort-characters-by-frequency/description/)|[java/py/js](./algorithms/SortCharactersByFrequency)|Medium|
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|215|[Kth Largest Element In An Array](https://leetcode-cn.com/problems/kth-largest-element-in-an-array/description/)|[java/py/js](./algorithms/KthLargestElementInAnArray)|Medium|
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# Database
319320
|#|Title|Solution|Difficulty|
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# Kth Largest Element In An Array
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We can solve this problem by max heap
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class Solution {
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class MaxHeap {
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ArrayList<Integer> heap;
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MaxHeap() {
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heap = new ArrayList<Integer>();
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}
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void push(int value) {
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heap.add(value);
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int pos = heap.size() - 1;
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int pPos = (pos % 2 == 0 ? pos - 2 : pos - 1) / 2;
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while (pPos >= 0 && value > heap.get(pPos)) {
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heap.set(pos, heap.get(pPos));
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heap.set(pPos, value);
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pos = pPos;
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pPos = (pos % 2 == 0 ? pos - 2 : pos - 1) / 2;
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}
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}
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int size() {
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return heap.size();
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}
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int pop() {
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int size = heap.size();
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if (size == 0)
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throw new ArrayIndexOutOfBoundsException("pop from empty list");
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else if (size == 1)
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return heap.remove(0);
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int value = heap.get(0);
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heap.set(0, heap.remove(size - 1));
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int pos = 0;
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int maxChildPos = pos * 2 + 2;
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if (maxChildPos < size - 1)
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maxChildPos = heap.get(maxChildPos) > heap.get(maxChildPos - 1) ? maxChildPos : maxChildPos - 1;
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else
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maxChildPos = maxChildPos - 1 < size - 1 ? maxChildPos - 1 : pos;
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while (maxChildPos < size - 1 && heap.get(pos) < heap.get(maxChildPos)) {
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int temp = heap.get(maxChildPos);
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heap.set(maxChildPos, heap.get(pos));
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heap.set(pos, temp);
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pos = maxChildPos;
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maxChildPos = pos * 2 + 2;
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if (maxChildPos < size - 1)
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maxChildPos = heap.get(maxChildPos) > heap.get(maxChildPos - 1) ? maxChildPos : maxChildPos - 1;
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else
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maxChildPos = maxChildPos - 1 < size - 1 ? maxChildPos - 1 : pos;
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}
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return value;
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}
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}
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public int findKthLargest(int[] nums, int k) {
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MaxHeap maxHeap = new MaxHeap();
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for (int num : nums)
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maxHeap.push(num);
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for (int i = 0; i < k - 1; i++)
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maxHeap.pop();
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return maxHeap.pop();
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}
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}
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/**
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* @param {number[]} nums
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* @param {number} k
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* @return {number}
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*/
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var findKthLargest = function(nums, k) {
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let maxHeap = new MaxHeap()
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nums.forEach(num => maxHeap.push(num))
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for (let i = 0; i < k - 1; i++)
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maxHeap.pop()
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return maxHeap.pop()
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};
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function MaxHeap() {
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this.heap = []
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};
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MaxHeap.prototype.push = function(value) {
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this.heap.push(value)
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let pos = this.heap.length - 1,
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pPos = (pos % 2 == 0 ? pos - 2 : pos - 1) / 2
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while (pPos >= 0 && value > this.heap[pPos]) {
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let temp = this.heap[pPos]
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this.heap[pPos] = value
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this.heap[pos] = temp
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pos = pPos
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pPos = (pos % 2 == 0 ? pos - 2 : pos - 1) / 2
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}
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};
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MaxHeap.prototype.size = function() {
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return this.heap.length
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};
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MaxHeap.prototype.pop = function() {
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let size = this.heap.length
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if (size == 0)
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throw new Error('pop form empty list')
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else if (size == 1)
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return this.heap.pop()
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let value = this.heap[0],
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pos = 0,
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maxChildPos = pos * 2 + 2
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this.heap[0] = this.heap.pop()
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if (maxChildPos < size - 1)
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maxChildPos = this.heap[maxChildPos] > this.heap[maxChildPos - 1] ? maxChildPos : maxChildPos - 1
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else
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maxChildPos = maxChildPos - 1 < size - 1 ? maxChildPos - 1 : pos
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while (maxChildPos < size - 1 && this.heap[pos] < this.heap[maxChildPos]) {
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let temp = this.heap[maxChildPos]
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this.heap[maxChildPos] = this.heap[pos]
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this.heap[pos] = temp
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pos = maxChildPos
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maxChildPos = pos * 2 + 2
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if (maxChildPos < size - 1)
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maxChildPos = this.heap[maxChildPos] > this.heap[maxChildPos - 1] ? maxChildPos : maxChildPos - 1
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else
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maxChildPos = maxChildPos - 1 < size - 1 ? maxChildPos - 1 : pos
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}
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return value
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};
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class Solution(object):
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class MaxHeap(object):
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def __init__(self):
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self.heap = []
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def push(self, value):
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self.heap.append(value)
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pos = len(self.heap) - 1
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p_pos = (pos - 2 if pos % 2 == 0 else pos - 1) / 2
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while p_pos >= 0 and value > self.heap[p_pos]:
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self.heap[pos], self.heap[p_pos] = self.heap[p_pos], self.heap[pos]
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pos = p_pos
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p_pos = (pos - 2 if pos % 2 == 0 else pos - 1) / 2
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def size(self):
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return len(self.heap)
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def pop(self):
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size = len(self.heap)
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if size == 0:
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raise IndexError('pop from empty list')
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elif size == 1:
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return self.heap.pop()
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value = self.heap[0]
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self.heap[0] = self.heap.pop()
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pos = 0
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max_child_pos = pos * 2 + 2
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if max_child_pos < size - 1:
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max_child_pos = max_child_pos if self.heap[max_child_pos] > self.heap[max_child_pos - 1] else max_child_pos - 1
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else:
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max_child_pos = max_child_pos - 1 if max_child_pos - 1 < size - 1 else pos
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while max_child_pos < size - 1 and self.heap[pos] < self.heap[max_child_pos]:
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self.heap[pos], self.heap[max_child_pos] = self.heap[max_child_pos], self.heap[pos]
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pos = max_child_pos
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max_child_pos = pos * 2 + 2
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if max_child_pos < size - 1:
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max_child_pos = max_child_pos if self.heap[max_child_pos] > self.heap[max_child_pos - 1] else max_child_pos - 1
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else:
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max_child_pos = max_child_pos - 1 if max_child_pos - 1 < size - 1 else pos
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return value
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def findKthLargest(self, nums, k):
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"""
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:type nums: List[int]
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:type k: int
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:rtype: int
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"""
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max_heap = Solution.MaxHeap()
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for num in nums:
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max_heap.push(num)
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for i in xrange(k - 1):
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max_heap.pop()
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return max_heap.pop()

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