32 lines
893 B
Go
32 lines
893 B
Go
// File: binary_search_edge.go
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// Created Time: 2023-08-23
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// Author: Reanon (793584285@qq.com)
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package chapter_searching
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/* Binary search for the leftmost target */
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func binarySearchLeftEdge(nums []int, target int) int {
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// Equivalent to finding the insertion point of target
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i := binarySearchInsertion(nums, target)
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// Did not find target, thus return -1
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if i == len(nums) || 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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func binarySearchRightEdge(nums []int, target int) int {
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// Convert to finding the leftmost target + 1
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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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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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