48 lines
1.5 KiB
Kotlin
48 lines
1.5 KiB
Kotlin
/**
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* File: binary_search_edge.kt
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* Created Time: 2024-01-25
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* Author: curtishd (1023632660@qq.com)
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*/
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package chapter_searching
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/* Binary search for the leftmost target */
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fun binarySearchLeftEdge(nums: IntArray, target: Int): Int {
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// Equivalent to finding the insertion point of target
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val i = binarySearchInsertion(nums, target)
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// Did not find target, thus return -1
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if (i == nums.size || nums[i] != target) {
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return -1
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}
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// Found target, return index i
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return i
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}
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/* Binary search for the rightmost target */
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fun binarySearchRightEdge(nums: IntArray, target: Int): Int {
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// Convert to finding the leftmost target + 1
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val i = binarySearchInsertion(nums, target + 1)
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// j points to the rightmost target, i points to the first element greater than target
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val j = i - 1
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// Did not find target, thus return -1
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if (j == -1 || nums[j] != target) {
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return -1
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}
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// Found target, return index j
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return j
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}
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/* Driver Code */
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fun main() {
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// Array with duplicate elements
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val nums = intArrayOf(1, 3, 6, 6, 6, 6, 6, 10, 12, 15)
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println("\nArray nums = ${nums.contentToString()}")
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// Binary search for left and right boundaries
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for (target in intArrayOf(6, 7)) {
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var index = binarySearchLeftEdge(nums, target)
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println("Index of the leftmost element $target = $index")
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index = binarySearchRightEdge(nums, target)
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println("Index of the rightmost element $target = $index")
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}
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} |