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Commit d658f9b

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author
kkarpyshev
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Merge remote-tracking branch 'origin/master'
2 parents 002f3ba + bcc86c9 commit d658f9b

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package medium
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import ArraysTopic
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import BinarySearchTopic
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import HeapTopic
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import MatrixTopic
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import SortingTopic
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/**
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* 1337. The K Weakest Rows in a Matrix
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* https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix/
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*
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You are given an m x n binary matrix mat of 1's (representing soldiers) and 0's (representing civilians).
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The soldiers are positioned in front of the civilians. That is, all the 1's will appear to the left of all the 0's in each row.
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A row i is weaker than a row j if one of the following is true:
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The number of soldiers in row i is less than the number of soldiers in row j.
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Both rows have the same number of soldiers and i < j.
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Return the indices of the k weakest rows in the matrix ordered from weakest to strongest.
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*/
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class Medium1337 : BinarySearchTopic, ArraysTopic, SortingTopic, HeapTopic, MatrixTopic {
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fun kWeakestRows(mat: Array<IntArray>, k: Int): IntArray {
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val soldies = IntArray(mat.size) { mat[it].sumBy { it } }
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return IntArray(k) {
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var min = Int.MAX_VALUE
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var index = 0
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for (j in soldies.indices) {
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if (soldies[j] < min) {
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min = soldies[j]
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index = j
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}
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}
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soldies[index] = Int.MAX_VALUE
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index
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}
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}
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}
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package medium
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import ArraysTopic
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import BinarySearchTopic
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/**
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* 81. Search in Rotated Sorted Array II
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* https://leetcode.com/problems/search-in-rotated-sorted-array/
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*
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There is an integer array nums sorted in non-decreasing order (not necessarily with distinct values).
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Before being passed to your function, nums is rotated at an unknown pivot index k (0 <= k < nums.length)
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such that the resulting array is [nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]] (0-indexed).
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For example, [0,1,2,4,4,4,5,6,6,7] might be rotated at pivot index 5 and become [4,5,6,6,7,0,1,2,4,4].
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Given the array nums after the rotation and an integer target, return true if target is in nums, or false if it is not in nums.
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You must decrease the overall operation steps as much as possible.
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BULLSHIT
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*/
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class Medium81 : BinarySearchTopic, ArraysTopic {
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fun search(nums: IntArray, target: Int): Boolean {
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val n = nums.size
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if (n == 0) return false
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var end = n - 1
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var start = 0
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while (start <= end) {
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val mid = start + (end - start) / 2
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if (nums[mid] == target) {
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return true
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}
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if (!isBinarySearchHelpful(nums, start, nums[mid])) {
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start++
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continue
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}
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// which array does pivot belong to.
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val pivotArray = existsInFirst(nums, start, nums[mid])
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// which array does target belong to.
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val targetArray = existsInFirst(nums, start, target)
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if (pivotArray xor targetArray) { // If pivot and target exist in different sorted arrays, recall that xor is true when both operands are distinct
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if (pivotArray) {
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start = mid + 1 // pivot in the first, target in the second
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} else {
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end = mid - 1 // target in the first, pivot in the second
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}
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} else { // If pivot and target exist in same sorted array
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if (nums[mid] < target) {
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start = mid + 1
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} else {
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end = mid - 1
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}
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}
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}
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return false
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}
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// returns true if we can reduce the search space in current binary search space
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private fun isBinarySearchHelpful(arr: IntArray, start: Int, element: Int): Boolean {
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return arr[start] != element
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}
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// returns true if element exists in first array, false if it exists in second
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private fun existsInFirst(arr: IntArray, start: Int, element: Int): Boolean {
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return arr[start] <= element
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}
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}
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fun main() {
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println(Medium81().search(intArrayOf(2, 5, 6, 0, 0, 1, 2), 0))
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println(Medium81().search(intArrayOf(2, 5, 6, 0, 0, 1, 2), 3))
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println(Medium81().search(intArrayOf(1, 0, 1, 1, 1), 0))
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}

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