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215 kth largest element in an array (#14)

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`18`	`18`	* [88. Merge Sorted Array](./src/0088_merge_sorted_array/msa.go)   `sort;`  `array`
`19`	`19`	* [167. Two Sum II - Input array is sorted](./src/0167_two_sum2/two_sum2.go)   `double index;`  `binary search`
`20`	`20`	* [209. Minimum Size Subarray Sum](./src/0209_minimum_size_subarray_sum/minimum_size_subarray_sum.go)   `sliding window`
	`21`	+* [215. Kth Largest Element in an Array](./src/0215_kth_largest_element_in_an_array/kthleiaa.go)   `sort`
`21`	`22`	* [283. Move Zeroes(solution1)](./src/0283_move_zeroes/move_zeroes.go)   `sliding window`
`22`	`23`	* [283. Move Zeroes(solution2)](./src/0283_move_zeroes/move_zeroes2.go)   `sliding window`
`23`	`24`	* [349. Intersection of Two Arrays](./src/0349_intersection_of_2_arrays/intersection_of_two_arrays.go)   `set`

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	`1`	`+/*`
	`2`	`+215. Kth Largest Element in an Array`
	`3`	`+https://leetcode.com/problems/kth-largest-element-in-an-array/`
	`4`	`+`
	`5`	`+Find the kth largest element in an unsorted array.`
	`6`	`+ Note that it is the kth largest element in the sorted order, not the kth distinct element.`
	`7`	`+`
	`8`	`+You may assume k is always valid, 1 ≤ k ≤ array's length.`
	`9`	`+`
	`10`	`+*/`
	`11`	`+`
	`12`	`+// time: 2018年12月22日`
	`13`	`+`
	`14`	`+package kthleiaa`
	`15`	`+`
	`16`	`+// heap sort`
	`17`	`+// time complexity: O(k * logn)`
	`18`	`+// sapce complexity: O(1)`
	`19`	`+func findKthLargest(nums []int, k int) int {`
	`20`	`+ // heapify`
	`21`	`+ for i := (len(nums) - 1) / 2; i >= 0; i-- {`
	`22`	`+ shiftDown(nums, len(nums), i)`
	`23`	`+ }`
	`24`	`+`
	`25`	`+ for i := len(nums) - 1; i >= len(nums)-k; i-- {`
	`26`	`+ nums[i], nums[0] = nums[0], nums[i]`
	`27`	`+ shiftDown(nums, i, 0)`
	`28`	`+ }`
	`29`	`+ return nums[len(nums)-k]`
	`30`	`+}`
	`31`	`+`
	`32`	`+func shiftDown(nums []int, n int, i int) {`
	`33`	`+ for 2*i+1 < n {`
	`34`	`+ j := 2*i + 1`
	`35`	`+ if j+1 < n && nums[j+1] > nums[j] {`
	`36`	`+ j++`
	`37`	`+ }`
	`38`	`+`
	`39`	`+ if nums[i] >= nums[j] {`
	`40`	`+ break`
	`41`	`+ }`
	`42`	`+ nums[j], nums[i] = nums[i], nums[j]`
	`43`	`+ i = j`
	`44`	`+ }`
	`45`	`+}`

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	`1`	`+package kthleiaa`
	`2`	`+`
	`3`	`+import "testing"`
	`4`	`+`
	`5`	`+func TestFindKthLargest(t *testing.T) {`
	`6`	`+ type arg struct {`
	`7`	`+ nums []int`
	`8`	`+ k int`
	`9`	`+ }`
	`10`	`+`
	`11`	`+ testCases := []arg{`
	`12`	`+ {nums: []int{3, 2, 1, 5, 6, 4}, k: 2},`
	`13`	`+ {nums: []int{3, 2, 3, 1, 2, 4, 5, 5, 6}, k: 4},`
	`14`	`+ }`
	`15`	`+`
	`16`	`+ expected := []int{5, 4}`
	`17`	`+`
	`18`	`+ for index, data := range testCases {`
	`19`	`+ if res := findKthLargest(data.nums, data.k); res != expected[index] {`
	`20`	`+ t.Errorf("expected %d, got %d", expected[index], res)`
	`21`	`+ }`
	`22`	`+ }`
	`23`	`+}`

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`34`	`34`	\|0167\|[Two Sum II - Input array is sorted](./0167_two_sum2/two_sum2.go)\|Easy\|`对撞指针(双索引)`\|
`35`	`35`	\|0198\|[House Robber](./0198_house_robber/house_robber.go)\|Easy\|`memory search;` `dynamic programming`\|
`36`	`36`	\|0209\|[Minimum Size Subarray Sum](./0209_minimum_size_subarray_sum/minimum_size_subarray_sum.go)\|Medium\|`sliding window`\|
	`37`	+\|0215\|[215. Kth Largest Element in an Array](0215_kth_largest_element_in_an_array/kthleiaa.go)\|Medium\|`sort`\|
`37`	`38`	\|0226\|[Invert Binary Tree](./0226_invert_binary_tree/invert_binary_tree.go)\|Easy\|`recursion; ` `binary tree`\|
`38`	`39`	\|0283\|[Move Zeroes(solution1)](./0283_move_zeroes/move_zeroes.go) <br/> [Move Zeroes(solution2)](./0283_move_zeroes/move_zeroes2.go)\|Easy\|`array`\|
`39`	`40`	\|0300\|[Longest Increasing Subsequence](./0300_longest_increasing_subsequence/lis.go)\|Medium\|`dp`\|

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