summaryrefslogtreecommitdiff
path: root/AlgoDesignAndTechniqueEdxJava/sources/BinarySearch.java
blob: 32fcb04443fe8c365abc366cd712cade963a0119 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class BinarySearch {

	public static void main(String[] args) {
		FastScanner scanner = new FastScanner(System.in);
		int n = scanner.nextInt();
		int[] a = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = scanner.nextInt();
		}
		int m = scanner.nextInt();
		int[] b = new int[m];
		for (int i = 0; i < m; i++) {
			b[i] = scanner.nextInt();
		}
		for (int i = 0; i < m; i++) {
			// replace with the call to binarySearch when implemented
			System.out.print(binarySearch(a, b[i]) + " ");
		}

	}

	public static int binarySearch(int[] a, int key) {
		return binarySearchRecursive(a, 0, a.length - 1, key);
	}

	public static int binarySearchRecursive(int[] a, int low, int high, int key) {
		if (high < low)
			return -1;
		int mid = (int) Math.floor(low + (high - low) / 2);
		if (key == a[mid]) {
			return mid;
		} else if (key < a[mid])
			return binarySearchRecursive(a, low, mid - 1, key);
		else
			return binarySearchRecursive(a, mid + 1, high, key);
	}

	static class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		FastScanner(InputStream stream) {
			try {
				br = new BufferedReader(new InputStreamReader(stream));
			} catch (Exception e) {
				e.printStackTrace();
			}
		}

		String next() {
			while (st == null || !st.hasMoreTokens()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}
	}

}