Input: A array arr[] of two elements having value 0 and 1
Output: Make both elements 0.
Specifications: Following are the specifications to follow.
1) It is guaranteed that one element is 0 but we do not know its position.
2) We can’t say about another element it can be 0 or 1.
3) We can only complement array elements, no other operation like and, or, multi, division, …. etc.
4) We can’t use if, else and loop constructs.
5) Obviously, we can’t directly assign 0 to array elements.
There are several ways we can do it as we are sure that always one Zero is there. Thanks to devendraiiit for suggesting following 3 methods.
Method 1
C++
#include <bits/stdc++.h> using namespace std; void changeToZero(int a[2]) { a[ a[1] ] = a[ !a[1] ]; } // Driver code int main() { int a[] = {1, 0}; changeToZero(a); cout<<"arr[0] = "<<a[0]<<endl; cout<<" arr[1] = "<<a[1]; return 0; } // This code is contributed by rathbhupendra |
C
void changeToZero(int a[2]) { a[ a[1] ] = a[ !a[1] ]; } int main() { int a[] = {1, 0}; changeToZero(a); printf(" arr[0] = %d \n", a[0]); printf(" arr[1] = %d ", a[1]); getchar(); return 0; } |
Python3
# Python3 program for a # boolean array puzzle def changeToZero(a): a[ a[1] ] = a[ not a[1] ] return a # Driver code if __name__=='__main__': a = [1, 0] a = changeToZero(a); print(" arr[0] = " + str(a[0])) print(" arr[1] = " + str(a[1])) # This code is contributed by Yash_R |
Method 2
void changeToZero(int a[2]) { a[ !a[0] ] = a[ !a[1] ] } |
Method 3
This method doesn’t even need complement.
void changeToZero(int a[2]) { a[ a[1] ] = a[ a[0] ] } |
Method 4
Thanks to purvi for suggesting this method.
void changeToZero(int a[2]) { a[0] = a[a[0]]; a[1] = a[0]; } |
There may be many more methods.
Please write comments if you find the above codes incorrect, or find other ways to solve the same problem.
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