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954c45864b
* docs: add Japanese documents (`ja/docs`) * docs: add Japanese documents (`ja/codes`) * docs: add Japanese documents * Remove pythontutor blocks in ja/ * Add an empty at the end of each markdown file. * Add the missing figures (use the English version temporarily). * Add index.md for Japanese version. * Add index.html for Japanese version. * Add missing index.assets * Fix backtracking_algorithm.md for Japanese version. * Add avatar_eltociear.jpg. Fix image links on the Japanese landing page. * Add the Japanese banner. --------- Co-authored-by: krahets <krahets@163.com>
49 lines
1.9 KiB
Java
49 lines
1.9 KiB
Java
/**
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* File: binary_search_edge.java
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* Created Time: 2023-08-04
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* Author: krahets (krahets@163.com)
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*/
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package chapter_searching;
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public class binary_search_edge {
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/* 最も左の target を二分探索 */
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static int binarySearchLeftEdge(int[] nums, int target) {
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// target の挿入点を見つけることと等価
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int i = binary_search_insertion.binarySearchInsertion(nums, target);
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// target を見つけられなかったので、-1 を返す
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if (i == nums.length || nums[i] != target) {
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return -1;
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}
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// target を見つけたので、インデックス i を返す
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return i;
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}
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/* 最も右の target を二分探索 */
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static int binarySearchRightEdge(int[] nums, int target) {
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// 最も左の target + 1 を見つけることに変換
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int i = binary_search_insertion.binarySearchInsertion(nums, target + 1);
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// j は最も右の target を指し、i は target より大きい最初の要素を指す
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int j = i - 1;
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// target を見つけられなかったので、-1 を返す
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if (j == -1 || nums[j] != target) {
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return -1;
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}
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// target を見つけたので、インデックス j を返す
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return j;
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}
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public static void main(String[] args) {
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// 重複要素を含む配列
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int[] nums = { 1, 3, 6, 6, 6, 6, 6, 10, 12, 15 };
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System.out.println("\n配列 nums = " + java.util.Arrays.toString(nums));
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// 左右の境界を二分探索
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for (int target : new int[] { 6, 7 }) {
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int index = binarySearchLeftEdge(nums, target);
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System.out.println("要素 " + target + " の最も左のインデックスは " + index);
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index = binarySearchRightEdge(nums, target);
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System.out.println("要素 " + target + " の最も右のインデックスは " + index);
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}
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}
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} |