算法图解笔记：第一章（java版）

二分查找：

优点：时间复杂度低，仅为logN

注意：前提是有序数组

Code：

public class Code_01_binarySearch {
	public static void main(String[] args) {
		//测试数组
		int[] myList = {1,3,5,7,9};
		System.out.println(binarySearch(myList, 7));
		System.out.println(binarySearch(myList, 10));
	}
	
	public static int binarySearch(int[] list,int item){
		int low = 0;
		int high = list.length - 1;
		while(low <= high){
			//定义中间位置
			int mid = low +(high - low)/2;
			int guess = list[mid];
			if(guess == item){
				return mid;
			}
			if(guess < item){
				low = mid + 1;
			}
			else{
				high = mid - 1;
			}
		}
		return -1;
	}
	
}