LeetCode Note Java 00704：Binary Search

二元搜尋法。

題目

Binary Search Easy

Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1.

You must write an algorithm with O(log n) runtime complexity.

我的解法

標準的二元搜尋法，設定左右兩邊界，每次測試兩邊界正中間的索引，是答案就回傳該索引，不是就修正邊界。

class Solution {
    public int search(int[] nums, int target) {
        int left = 0;
        int right = nums.length - 1;
        while (left <= right) {
          int middle = (left + right) / 2;
          int value = nums[middle];
          if (value == target) {
            return middle;
          }
          if (value < target) {
            left = middle + 1;
          } else {
            right = middle - 1;
          }
        }
        return -1;
    }
}