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14c314c08c
* Retranslate the complete English edition from Simplified Chinese * Polish three English explanations after reader-focused review
65 lines
2.2 KiB
JavaScript
65 lines
2.2 KiB
JavaScript
/**
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* File: binary_search_insertion.js
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* Created Time: 2023-08-22
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* Author: Gaofer Chou (gaofer-chou@qq.com)
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*/
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/* Find an insertion point using binary search (no duplicates) */
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function binarySearchInsertionSimple(nums, target) {
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let i = 0,
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j = nums.length - 1; // Initialize the closed interval [0, n-1]
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while (i <= j) {
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const m = Math.floor(i + (j - i) / 2); // Calculate midpoint index m, using Math.floor() to round down
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if (nums[m] < target) {
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i = m + 1; // Target must be in [m+1, j] if it exists
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} else if (nums[m] > target) {
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j = m - 1; // Target must be in [i, m-1] if it exists
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} else {
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return m; // Target was found; return insertion point m
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}
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}
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// Target was not found; return insertion point i
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return i;
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}
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/* Find an insertion point using binary search (with duplicates) */
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function binarySearchInsertion(nums, target) {
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let i = 0,
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j = nums.length - 1; // Initialize the closed interval [0, n-1]
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while (i <= j) {
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const m = Math.floor(i + (j - i) / 2); // Calculate midpoint index m, using Math.floor() to round down
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if (nums[m] < target) {
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i = m + 1; // Target must be in [m+1, j] if it exists
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} else if (nums[m] > target) {
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j = m - 1; // Target must be in [i, m-1] if it exists
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} else {
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j = m - 1; // Continue in [i, m-1] to find the rightmost element smaller than target
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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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/* Driver code */
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// Array with no duplicate elements
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let nums = [1, 3, 6, 8, 12, 15, 23, 26, 31, 35];
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console.log('\nArray nums = ' + nums);
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// Find an insertion point using binary search
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for (const target of [6, 9]) {
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const index = binarySearchInsertionSimple(nums, target);
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console.log('Element ' + target + ' has insertion index ' + index);
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}
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// Array containing duplicate elements
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nums = [1, 3, 6, 6, 6, 6, 6, 10, 12, 15];
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console.log('\nArray nums = ' + nums);
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// Find an insertion point using binary search
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for (const target of [2, 6, 20]) {
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const index = binarySearchInsertion(nums, target);
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console.log('Element ' + target + ' has insertion index ' + index);
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}
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module.exports = {
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binarySearchInsertion,
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};
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