Move the Spaces to Front of the String

Problem: Given a string that has set of words and spaces, write a program to move the spaces to front of string, you need to traverse the array only once and need to adjust the string in place.
string = “move these spaces to beginning”
output =” movethesepacestobeginning”

Solution:

Maintain two indices i and j.
Traverse from end to beginning.
If the current index contains char, swap chars in index i with index j.
This will move all the spaces to beginning of the array.

#include<iostream>  
using namespace std;  
int main()  
{  
    char a\[\]="Move space to begining";  
    int n=strlen(a)-1,count = n;  
   
    //MoveSpace(a,0,strlen(a)-1);  
    for(int i=n;i>=0;i--)  
    {  
        if(a\[i\] != ' ')  
        a\[count--\] = a\[i\];  
    }  
       
    while(count>=0)  
        a\[count--\] = ' ';  
    cout << "After Space Moved to Begining" << a << endl;  
   
    return 0;  
}

Time Complexity: O(n) where n is the number of characters in input array.
Space Complexity: O(1).

See also