Given an array “a[]” and integer “b”. Find whether b is present in a[] or not. If present, then double the value of b and search again. We repeat these steps until b is not found. Finally we return value of b.
Examples:
Input : a[] = {1, 2, 3}
b = 1
Output :4
Initially we start with b = 1. Since
it is present in array, it becomes 2.
Now 2 is also present in array b becomes 4 .
Since 4 is not present, we return 4.
Input : a[] = {1 3 5 2 12}
b = 3
Output :6
Question Source : Asked in Yatra.com Online Test
1) Sort the input array.
2) Keep doing binary search and doubling until the element is not present.
The below code using binary_search() in STL
C++
// C++ program to repeatedly search an element by // doubling it after every successful search #include <bits/stdc++.h> using namespace std; int findElement(int a[], int n, int b) { // Sort the given array so that binary search // can be applied on it sort(a, a + n); int max = a[n - 1]; // Maximum array element while (b < max) { // search for the element b present or // not in array if (binary_search(a, a + n, b)) b *= 2; else return b; } return b; } // Driver code int main() { int a[] = { 1, 2, 3 }; int n = sizeof(a) / sizeof(a[0]); int b = 1; cout << findElement(a, n, b); return 0; } |
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Java
// Java program to repeatedly search an element by // doubling it after every successful search import java.util.Arrays; public class Test4 { static int findElement(int a[], int n, int b) { // Sort the given array so that binary search // can be applied on it Arrays.sort(a); int max = a[n - 1]; // Maximum array element while (b < max) { // search for the element b present or // not in array if (Arrays.binarySearch(a, b) > -1) b *= 2; else return b; } return b; } // Driver code public static void main(String args[]) { int a[] = { 1, 2, 3 }; int n = a.length; int b = 1; System.out.println(findElement(a, n, b)); } } // This article is contributed by Sumit Ghosh |
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Python
# Python program to repeatedly search an element by # doubling it after every successful search def binary_search(a, x, lo = 0, hi = None): if hi is None: hi = len(a) while lo < hi: mid = (lo + hi)//2 midval = a[mid] if midval < x: lo = mid + 1 elif midval > x: hi = mid else: return mid return -1 def findElement(a, n, b): # Sort the given array so that binary search # can be applied on it a.sort() mx = a[n - 1] # Maximum array element while (b < max): # search for the element b present or # not in array if (binary_search(a, b, 0, n) != -1): b *= 2 else: return b return b # Driver code a = [ 1, 2, 3 ] n = len(a) b = 1print findElement(a, n, b) # This code is contributed by Sachin Bisht |
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C#
// C# program to repeatedly search an // element by doubling it after every // successful search using System; public class GFG { static int findElement(int[] a, int n, int b) { // Sort the given array so that // binary search can be applied // on it Array.Sort(a); // Maximum array element int max = a[n - 1]; while (b < max) { // search for the element b // present or not in array if (Array.BinarySearch(a, b) > -1) b *= 2; else return b; } return b; } // Driver code public static void Main() { int[] a = { 1, 2, 3 }; int n = a.Length; int b = 1; Console.WriteLine(findElement(a, n, b)); } } // This code is contributed by vt_m. |
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PHP
<?php // Php program to repeatedly search an element by // doubling it after every successful search function binary_search($a, $x, $lo=0, $hi=NULL) { if ($hi == NULL) $hi = count($a); while ($lo < $hi) { $mid = ($lo + $hi) / 2; $midval = $a[$mid]; if ($midval < $x) $lo = $mid + 1; else if ($midval > $x) $hi = $mid; else return $mid; } return -1; } function findElement($a, $n, $b) { // Sort the given array so that binary search // can be applied on it sort($a); $mx = $a[$n - 1]; // Maximum array element while ($b < max($a)) { // search for the element b present or // not in array if (binary_search($a, $b, 0, $n) != -1) $b *= 2; else return $b; } return $b; } // Driver code $a = array(1, 2, 3 ); $n = count($a); $b = 1; echo findElement($a, $n, $b); // This code is contributed by Srathore ?> |
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Output:
4
This article is contributed by Karan Kumar Gautam. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
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