算法之二分查找(java版实现加测试)

import edu.princeton.cs.algs4.*;
public class Main{
public static int rank(int key,int[] a)
{
int deep = 0;
return rank(key,a,0,a.length - 1,deep);
}
public static int rank(int key,int[] a,int lo,int hi,int deep)
{
if(lo > hi) return -1;
int mid = lo + (hi - lo) / 2;
if(a[mid] > key)
{
StdOut.printf("deep: %d lo: %d hi: %d\n",deep,lo,hi);
++deep;
return rank(key,a,lo,mid - 1,deep);
}
else if(a[mid] < key)
{
StdOut.printf("deep: %d lo: %d hi: %d\n",deep,lo,hi);
++deep;
return rank(key,a,mid + 1,hi,deep);
}
else
{
StdOut.printf("deep: %d lo: %d hi: %d\n",deep,lo,hi);
return mid;
}
}
public static void main(String[] args)
{
int M = 10;
int[] a = new int[M];
for(int i = 0; i < M; ++i)
a[i] = i;
StdOut.printf("%d",rank(9,a));
}
}

public static void test(String mode,String file)
{
In in = new In(file);
int[] a = in.readAllInts();
Arrays.sort(a);
//"+"打印出不在白名单中的数
if(mode == "+")
{
while(!StdIn.isEmpty())
{
int key = StdIn.readInt();
if(rank(key,a) == -1)
{
StdOut.printf("%d is not in whitelist\n", key);
}
}
}
//"-"打印出在白名单中的数
if(mode == "-")
{
while(!StdIn.isEmpty())
{
int key = StdIn.readInt();
if(rank(key,a) != -1)
StdOut.printf("%d is in whitelist\n",key);
}
}
}

public static void main(String[] args)
{
test("-","test.txt");
}

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(a[mid] > key) hi = mid - 1;
else if(a[mid] < key) lo = mid + 1;
else return mid;
}
return -1;
}

public static void test(String mode,String file)
{
In in = new In(file);
int[] a = in.readAllInts();
Arrays.sort(a);
//"+"打印出不在白名单中的数
if(mode == "+")
{
while(!StdIn.isEmpty())
{
int key = StdIn.readInt();
if(rank(key,a) == -1)
{
StdOut.printf("%d is not in whitelist\n", key);
}
}
}
//"-"打印出在白名单中的数
if(mode == "-")
{
while(!StdIn.isEmpty())
{
int key = StdIn.readInt();
if(rank(key,a) != -1)
StdOut.printf("%d is in whitelist\n",key);
}
}
}

public static void main(String[] args)
{
test("-","test.txt");
}