public class ErFenChaoZhao {
public static int binarySearch(int[] list, int key) {
int low = 0;
int high = list.length -1;
while (high >= low) {
int mid = (low +high) /2;
if(key <list[mid]) {
high = mid -1;
}
else if(key == list[mid]) {
return mid;
}else {
low = mid +1;
}
}
return -low -1;
}
public static void main(String[] args) {
System.out.println("jveejjvd: ");
int[] list = {1, 9, 4, 2, 5, -3, 6, 5};
int i = ErFenChaoZhao.binarySearch(list, 4);
System.out.println(i);
}
}
结果
jveejjvd:
-7
二分查找的前提是数组是有序数组,你这个是无序数组,不能使用二分查找的
先用冒泡啥的对list数据进行排序,然后再二分查找
需要先对int[] list = {1, 9, 4, 2, 5, -3, 6, 5};按从小到大排序,然后再查找,但是一排序,原来的顺序就变了,因此这个序列不适合二分法查找。还是从头遍历一次吧。