mirror of
https://github.com/krahets/hello-algo.git
synced 2024-12-26 21:06:29 +08:00
70784a1ec3
* feat(chapter_dynamic_programming): Add js and ts codes for chapter 14.1 * style(chapter_dynamic_programming): format code * refactor(chapter_dynamic_programming): remove main definition and add type * feat(chapter_backtracking): Add js and ts codes for chapter 13.3 * feat(chapter_divide_and_conquer): Add js and ts codes for chapter 12.2 * feat(chapter_divide_and_conquer): Add js and ts codes for chapter 12.3 * feat(chapter_divide_and_conquer): Add js and ts codes for chapter 12.4 * style(chapter_divide_and_conquer): fix typo * refactor: Use === instead of == in js and ts
39 lines
1 KiB
JavaScript
39 lines
1 KiB
JavaScript
/**
|
|
* File: binary_search_recur.js
|
|
* Created Time: 2023-07-30
|
|
* Author: yuan0221 (yl1452491917@gmail.com)
|
|
*/
|
|
|
|
/* 二分查找：问题 f(i, j) */
|
|
function dfs(nums, target, i, j) {
|
|
// 若区间为空，代表无目标元素，则返回 -1
|
|
if (i > j) {
|
|
return -1;
|
|
}
|
|
// 计算中点索引 m
|
|
const m = i + ((j - i) >> 1);
|
|
if (nums[m] < target) {
|
|
// 递归子问题 f(m+1, j)
|
|
return dfs(nums, target, m + 1, j);
|
|
} else if (nums[m] > target) {
|
|
// 递归子问题 f(i, m-1)
|
|
return dfs(nums, target, i, m - 1);
|
|
} else {
|
|
// 找到目标元素，返回其索引
|
|
return m;
|
|
}
|
|
}
|
|
|
|
/* 二分查找 */
|
|
function binarySearch(nums, target) {
|
|
const n = nums.length;
|
|
// 求解问题 f(0, n-1)
|
|
return dfs(nums, target, 0, n - 1);
|
|
}
|
|
|
|
/* Driver Code */
|
|
const target = 6;
|
|
const nums = [1, 3, 6, 8, 12, 15, 23, 26, 31, 35];
|
|
// 二分查找（双闭区间）
|
|
const index = binarySearch(nums, target);
|
|
console.log(`目标元素 6 的索引 = ${index}`);
|