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62 lines
2.0 KiB
62 lines
2.0 KiB
/*
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* File: binary_search_insertion.rs
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* Created Time: 2023-08-30
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* Author: night-cruise (2586447362@qq.com)
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*/
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#![allow(unused)]
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/* 二分搜尋插入點（無重複元素） */
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fn binary_search_insertion_simple(nums: &[i32], target: i32) -> i32 {
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let (mut i, mut j) = (0, nums.len() as i32 - 1); // 初始化雙閉區間 [0, n-1]
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while i <= j {
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let m = i + (j - i) / 2; // 計算中點索引 m
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if nums[m as usize] < target {
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i = m + 1; // target 在區間 [m+1, j] 中
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} else if nums[m as usize] > target {
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j = m - 1; // target 在區間 [i, m-1] 中
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} else {
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return m;
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}
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}
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// 未找到 target ，返回插入點 i
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i
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}
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/* 二分搜尋插入點（存在重複元素） */
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pub fn binary_search_insertion(nums: &[i32], target: i32) -> i32 {
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let (mut i, mut j) = (0, nums.len() as i32 - 1); // 初始化雙閉區間 [0, n-1]
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while i <= j {
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let m = i + (j - i) / 2; // 計算中點索引 m
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if nums[m as usize] < target {
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i = m + 1; // target 在區間 [m+1, j] 中
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} else if nums[m as usize] > target {
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j = m - 1; // target 在區間 [i, m-1] 中
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} else {
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j = m - 1; // 首個小於 target 的元素在區間 [i, m-1] 中
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}
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}
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// 返回插入點 i
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i
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}
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/* Driver Code */
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fn main() {
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// 無重複元素的陣列
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let nums = [1, 3, 6, 8, 12, 15, 23, 26, 31, 35];
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println!("\n陣列 nums = {:?}", nums);
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// 二分搜尋插入點
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for target in [6, 9] {
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let index = binary_search_insertion_simple(&nums, target);
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println!("元素 {} 的插入點的索引為 {}", target, index);
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}
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// 包含重複元素的陣列
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let nums = [1, 3, 6, 6, 6, 6, 6, 10, 12, 15];
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println!("\n陣列 nums = {:?}", nums);
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// 二分搜尋插入點
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for target in [2, 6, 20] {
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let index = binary_search_insertion(&nums, target);
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println!("元素 {} 的插入點的索引為 {}", target, index);
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}
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}
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