【算法】第一章

###1.1.10 二分法查找 關鍵代碼

public 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;
		return key;
	}
	return -1;
}