Copyright Notice
- This article original author: Columbia Valley's younger brother
- Author blog address: http://blog.csdn.net/lfdfhl
Principle analysis
There is an ordered array {2, 5, 8, 12, 16, 23, 38, 56, 72, 91 }, please use the dichotomy to find the index corresponding to element 23.
Precondition
The premise of binary search is that the elements in the array are ordered, otherwise it cannot be searched.
Search principle
first step:
Determine the maximum, minimum, and middle subscripts of the entire array
The second step:
Compare the target value with the value corresponding to the maximum subscript, the value corresponding to the minimum subscript, and the value corresponding to the middle subscript
third step:
Adjust maximum subscript, minimum subscript, middle subscript
Find process
Code
The code implementation of binary search is as follows:
package com.algorithm;
/**
* 本文作者：谷哥的小弟
* 博客地址：http://blog.csdn.net/lfdfhl
*
*/
public class BinarySearch {
public static void main(String[] args) {
int[] intArray = {
2, 5, 8, 12, 16, 23, 38, 56, 72, 91 };
int index = binarySearch(intArray, 23);
System.out.println(index);
}
public static int binarySearch(int[] intArray, int value) {
int max = intArray.length - 1;
int min = 0;
int mid = (max + min) / 2;
while (intArray[mid] != value) {
if (min <= max) {
if (intArray[mid] > value) {
max = mid - 1;
} else if (intArray[mid] < value) {
min = mid + 1;
}
mid = (max + min) / 2;
} else {
System.out.println("未查询到相应数据");
mid = -1;
break;
}
}
return mid;
}
}
operation result
