二分查找法

最基本的二分查找法、不考虑数组有重复数据、匹配到返回具体元素、没有返回-1

public class TestBinary {
    public int binarySearch(int[] array, int key){

        int left = 0;
        int right = array.length -1;


        while (left <= right){
            int mid = (left+right)/2;
            if (array[mid] == key){
                return array[mid];
            }else if (array[mid] < key){
                left = mid +1;
            }else {
                right = mid -1;
            }
        }

        return -1;
    }

    public static void main(String[] args) {
        int[] a = {10,20,30,40,50};
        int i = new TestBinary().binarySearch(a, 10);
        System.out.println("i = " + i);
    }
}