Software--DataStructureAndAlgorithm

Algorithm 核心算法。

1. BinarySearch

public class BinarySearchRank {

    public static int rank(int key, int[] a){
        int lo = 0;
        int hi = a.length - 1;
        while(lo <= hi){
            int mid = lo + (hi - lo)/2;
            if (key < a[mid]) hi = mid - 1;
            else if(key > a[mid]) lo = mid + 1;
            else return mid;
        }
        return -1;
    }
}