72 lines
2.3 KiB
Swift
72 lines
2.3 KiB
Swift
/**
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* File: binary_search_insertion.swift
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* Created Time: 2023-08-06
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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/* Binary search for insertion point (no duplicate elements) */
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func binarySearchInsertionSimple(nums: [Int], target: Int) -> Int {
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// Initialize double closed interval [0, n-1]
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var i = nums.startIndex
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var j = nums.endIndex - 1
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while i <= j {
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let m = i + (j - i) / 2 // Calculate midpoint index m
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if nums[m] < target {
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i = m + 1 // Target is in interval [m+1, j]
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} else if nums[m] > target {
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j = m - 1 // Target is in interval [i, m-1]
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} else {
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return m // Found target, return insertion point m
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}
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}
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// Did not find target, return insertion point i
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return i
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}
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/* Binary search for insertion point (with duplicate elements) */
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public func binarySearchInsertion(nums: [Int], target: Int) -> Int {
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// Initialize double closed interval [0, n-1]
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var i = nums.startIndex
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var j = nums.endIndex - 1
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while i <= j {
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let m = i + (j - i) / 2 // Calculate midpoint index m
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if nums[m] < target {
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i = m + 1 // Target is in interval [m+1, j]
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} else if nums[m] > target {
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j = m - 1 // Target is in interval [i, m-1]
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} else {
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j = m - 1 // First element less than target is in interval [i, m-1]
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}
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}
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// Return insertion point i
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return i
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}
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#if !TARGET
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@main
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enum BinarySearchInsertion {
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/* Driver Code */
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static func main() {
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// Array without duplicate elements
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var nums = [1, 3, 6, 8, 12, 15, 23, 26, 31, 35]
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print("\nArray nums = \(nums)")
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// Binary search for insertion point
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for target in [6, 9] {
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let index = binarySearchInsertionSimple(nums: nums, target: target)
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print("The insertion point index of element \(target) is \(index)")
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}
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// Array with duplicate elements
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nums = [1, 3, 6, 6, 6, 6, 6, 10, 12, 15]
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print("\nArray nums = \(nums)")
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// Binary search for insertion point
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for target in [2, 6, 20] {
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let index = binarySearchInsertion(nums: nums, target: target)
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print("The insertion point index of element \(target) is \(index)")
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}
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}
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}
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#endif
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