/*
 * @Description: 二分查找
 * @Version: 2.0
 * @Autor: zhuyijun
 * @Date: 2021-03-29 09:08:50
 * @LastEditors: zhuyijun
 * @LastEditTime: 2021-03-29 17:35:47
 */
package main

import "fmt"

/**
二分查找算法
*/
func BinarySearch(key int, a []int) int {
	lo := 0
	hi := len(a) - 1
	for lo < hi {
		mid := lo + (hi-lo)/2
		if key < a[mid] {
			hi = mid - 1
		} else if key > a[mid] {
			lo = mid + 1
		} else {
			return mid
		}
	}
	return -1
}
func main() {
	var a = []int{0, 2, 4, 7, 9, 11, 45, 67, 99, 100}
	var i int = 2
	key := BinarySearch(i, a)
	if key > 0 {
		fmt.Printf("已查到:%d,位置在:%d \n", i, key+1)
	} else {
		fmt.Printf("没有查到a数组中有%d", i)
	}
}