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BinarySearch.java
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BinarySearch.java
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package Algorithms;
public class BinarySearch {
public static void main(String[] strs) {
BinarySearch bs = new BinarySearch();
int[] num = new int[]{0,1,2,3,4,5};
int target = 9;
System.out.print(bs.binarySearch(num, target));
//int[] num2 = new int[0];
//System.out.print(bs.binarySearch(num2, target));
}
public int binarySearch(int num[], int target) {
if (num == null || num.length == 0) {
return -1;
}
int left = 0;
int right = num.length - 1;
String test = "test";
String t2 = test.substring(0,0);
System.out.printf(test.substring(0,0));
// while (left <= right) {
// int mid = left + (right - left)/2;
// if (num[mid] > target) {
// right = mid - 1;
// } else if (num[mid] < target) {
// left = mid + 1;
// } else {
// return mid;
// }
// }
// [1, 2]
while (left + 1 < right) {
int mid = left + (right - left)/2;
if (num[mid] > target) {
right = mid;
} else if (num[mid] < target) {
left = mid;
} else {
return mid;
}
}
if (num[left] == target) {
return left;
} else if (num[right] == target) {
return right;
}
return -1;
}
}