You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
40 lines
1.0 KiB
40 lines
1.0 KiB
/**
|
|
* 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}`);
|