Considere una serie de números compuesta únicamente por los dígitos 4 y 7. Los primeros números de la serie son 4, 7, 44, 47, 74, 77, 444, .. etc. Dado un número formado por 4, 7 dígitos únicamente, necesitamos encontrar la posición de este número en esta serie.
Ejemplos:
C++
// C++ program to find position of a number
// in a series of numbers with 4 and 7 as the
// only digits.
#include <iostream>
#include <algorithm>
using namespace std;
int findpos(string n)
{
int i = 0, pos = 0;
while (n[i] != '\0') {
// check all digit position
switch (n[i])
{
// if number is left then pos*2+1
case '4':
pos = pos * 2 + 1;
break;
// if number is right then pos*2+2
case '7':
pos = pos * 2 + 2;
break;
}
i++;
}
return pos;
}
// Driver code
int main()
{
// given a number which is constructed
// by 4 and 7 digit only
string n = "774";
cout << findpos(n);
return 0;
}
Java
// java program to find position of a number
// in a series of numbers with 4 and 7 as the
// only digits.
import java.util.*;
class GFG {
static int findpos(String n)
{
int k = 0, pos = 0, i = 0;
while (k != n.length()) {
// check all digit position
switch (n.charAt(i)) {
// if number is left then pos*2+1
case '4':
pos = pos * 2 + 1;
break;
// if number is right then pos*2+2
case '7':
pos = pos * 2 + 2;
break;
}
i++;
k++;
}
return pos;
}
// Driver code
public static void main(String[] args)
{
// given a number which is constructed
// by 4 and 7 digit only
String n = "774";
System.out.println(findpos(n));
}
}
// This code is contributed by Sam007.
Python3
# python program to find position # of a number in a series of # numbers with 4 and 7 as the # only digits. def findpos(n): i = 0 j = len(n) pos = 0 while (i<j): # check all digit position # if number is left then # pos*2+1 if(n[i] == '4'): pos = pos * 2 + 1 # if number is right then # pos*2+2 if(n[i] == '7'): pos = pos * 2 + 2 i= i+1 return pos # Driver code # given a number which is constructed # by 4 and 7 digit only n = "774" print(findpos(n)) # This code is contributed by Sam007
C#
// C# program to find position of
// a number in a series of numbers
// with 4 and 7 as the only digits.
using System;
class GFG
{
static int findpos(String n)
{
int k = 0, pos = 0, i = 0;
while (k != n.Length) {
// check all digit position
switch (n[i]) {
// if number is left then pos*2+1
case '4':
pos = pos * 2 + 1;
break;
// if number is right then pos*2+2
case '7':
pos = pos * 2 + 2;
break;
}
i++;
k++;
}
return pos;
}
// Driver code
static void Main()
{
// given a number which is constructed
// by 4 and 7 digit only
String n = "774";
Console.Write(findpos(n));
}
}
// This code is contributed by Sam007
PHP
<?php
// PHP program to find position of a number
// in a series of numbers with 4 and 7 as the
// only digits.
function findpos($n)
{
$i = 0;
$pos = 0;
while($i < strlen($n)) {
// check all digit position
switch ($n[$i])
{
// if number is left then pos*2+1
case '4':
$pos = $pos * 2 + 1;
break;
// if number is right then pos*2+2
case '7':
$pos = $pos * 2 + 2;
break;
}
$i++;
}
return $pos;
}
// Driver code
// given a number which
// is constructed by 4
// and 7 digit only
$n = "774";
echo findpos($n);
// This code is contributed by Sam007
?>
Javascript
<script>
// Javascript program to find position of a number
// in a series of numbers with 4 and 7 as the
// only digits.
function findpos(n)
{
let i = 0;
let pos = 0;
while(i < n.length) {
// check all digit position
switch (n[i])
{
// if number is left then pos*2+1
case '4':
pos = pos * 2 + 1;
break;
// if number is right then pos*2+2
case '7':
pos = pos * 2 + 2;
break;
}
i++;
}
return pos;
}
// Driver code
// given a number which
// is constructed by 4
// and 7 digit only
let n = "774";
document.write(findpos(n));
// This code is contributed by _saurabh_jaiswal
</script>
Publicación traducida automáticamente
Artículo escrito por GeeksforGeeks-1 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA