Find the n | C ++ program to find n - th number whose binary representation is palindrome . ; Finds if the kth bit is set in the binary representation ; Returns the position of leftmost set bit in the binary representation ; Finds whether the integer in binary representation is palindrome or not ; One by one compare bits ; Compare left and right bits and converge ; Start from 1 , traverse through all the integers ; If we reach n , break the loop ; Driver code ; Function Call
#include <bits/stdc++.h> NEW_LINE using namespace std ; int isKthBitSet ( int x , int k ) { return ( x & ( 1 << ( k - 1 ) ) ) ? 1 : 0 ; } int leftmostSetBit ( int x ) { int count = 0 ; while ( x ) { count ++ ; x = x >> 1 ; } return count ; } int isBinPalindrome ( int x ) { int l = leftmostSetBit ( x ) ; int r = 1 ; while ( l > r ) { if ( isKthBitSet ( x , l ) != isKthBitSet ( x , r ) ) return 0 ; l -- ; r ++ ; } return 1 ; } int findNthPalindrome ( int n ) { int pal_count = 0 ; int i = 0 ; for ( i = 1 ; i <= INT_MAX ; i ++ ) { if ( isBinPalindrome ( i ) ) { pal_count ++ ; } if ( pal_count == n ) break ; } return i ; } int main ( ) { int n = 9 ; cout << findNthPalindrome ( n ) ; }