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BinarySearch.java
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38 lines (35 loc) · 1.12 KB
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import com.sun.tools.javac.comp.Lower;
/**
* @program JavaBooks
* @description: 二分查找
* @author: mf
* @create: 2019/10/02 16:45
*/
/*
二分查找
*/
/*
思想：在有序列表中，取中间记录作为比较对象，若给定值与中间记录的关键词相等，则查找成功；
若给定值小于中间记录的关键词，则在中间记录的左半区继续查找；
若给定值大于中间的关键字，则在中间记录的右半区继续查找。
不断重复上述锅中，直到查找成功。
*/
public class BinarySearch {
public static void main(String[] args) {
int[] arr = {0, 1, 16, 24, 35, 47, 59, 62};
System.out.println(binarySearch(arr, 59));
}
private static int binarySearch(int[] arr, int target) {
if (arr == null || arr.length == 0) return 0;
int left = 0;
int right = arr.length;
int mid;
while (left < right) {
mid = (left + right) >> 1;
if (target < arr[mid]) right = mid - 1;
else if (target > arr[mid]) left = mid + 1;
else return mid;
}
return 0;
}
}