CareerCup

# Write a function accepting a string with numbers 
# and letters that reverses the letters of the string 
# but leave numbers in the same position. 

def process_str(input_str):
    output_str = ""
    num_pos = []
    nums = []
    idx = 0
    for char in input_str:
        try:
            s = int(char)
            num_pos.append(idx)
            nums.append(s)
        except:
            output_str = char + output_str
        idx+=1
    for i in range(0,len(num_pos)):
        output_str = putanum(output_str, nums[i], num_pos[i])
    return output_str

def putanum(string, num, pos):
    str_head = string[:pos]
    str_tail = string[pos:]
    return str_head+str(num)+str_tail

if __name__=="__main__":
    print "str1ngw1thnumb3rs"
    print process_str("str1ngw1thnumb3rs")

public static String reverseString(String s) {
        //base case
        if(s == null || s.length() <= 1) {
            return s;
        }
        char[] arr = s.toCharArray();

        int k = arr.length-1;
        int i = 0;

        while(i < k) {

            if(arr[i] >= '0' && arr[i] <= '9') {   i++; }
            if(arr[k] >= '0' && arr[k] <= '9') {   k--; }
                
            if (i < k) {
                //swap the elements
                char temp = arr[i];
                arr[i] =arr[k];
                arr[k] = temp;
            }
            i++; k--;
            
        }

        return    String.valueOf(arr);

}

I think the example output is incorrect. If the numbers are suppose to be in the same position, then the '3' at the end of the output string is in the incorrect place. In addition, it is unclear what happens when a letter should be swapped with a number. Do both the letter and the number stay in the same place? Or does the letter get swapped with the next possible letter? I list both outputs below

Input: str1ngw1thnumb3rs
Output as listed: srb1mun1htwgn3rts

Corrected output if letter/number pairs stay in the same place: srr1mun1thwgnb3ts
Corrected output if we remove the numbers, reverse the string, and re-insert numbers: srb1mun1htwgnr3ts

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;



public class StringReverse {
public static void main(String[] args) {
String str= "str90ngw1thnumb3rs";
StringBuilder withoutnum = new StringBuilder();
Map<Integer,String> map = new HashMap<>();
Pattern pat = Pattern.compile("\\d+");
Matcher match = pat.matcher(str);
while(match.find())
{
map.put(match.start(), match.group());
}

Pattern pat1 = Pattern.compile("[a-z]");
Matcher match1 = pat1.matcher(str);
while(match1.find())
{
withoutnum.append(match1.group());
}

Iterator it = map.keySet().iterator();
while(it.hasNext())
{
int i=(int) it.next();
withoutnum.reverse().insert(i, map.get(i));
}
System.out.println(withoutnum.toString());
}
}

def process_str(input_str):
	digit_index_list = [i for i in range(0,len(input_str)) if input_str[i].isdigit()]
	alpha_list_reversed = [c for c in input_str[::-1] if c.isalpha()]
	
	output_list = alpha_list_reversed
	for i in digit_index_list:
		output_list.insert(i, input_str[i])
	
	return "".join(output_list)

I think the example output is wrong.

public static String swapString(String str)
    {
        char[] charArr = str.toCharArray();
        int len = charArr.length, leftP = 0, rightP = len-1;
        while( leftP < rightP)
        {
            if(charArr[leftP] < '0' || charArr[leftP] > '9')
            {
                while((charArr[rightP] >=  '0') && (charArr[rightP] <='9')) {--rightP;}
                swap(charArr, leftP, rightP);
                --rightP;
            }
            ++leftP;
        }
        
        return new String(charArr);

}

In C++:

#include <iostream>
#include <cctype>
#include <string>
using namespace std;

string& reverseLetters(string& dest, const string& src)
{
    dest.clear();
    dest.resize(src.size());
    
    for(int i = 0, j = src.size() - 1; j >= 0; ){
        if(isdigit(src[i])){
            dest[i] = src[i];
            ++i;
        }
        else if(isdigit(src[j])) --j;
        else{
             dest[i] = src[j];
             ++i;
             --j;
        }
    }
    return dest;
}

int main()
{
    string t, s = "str1ngw1thnumb3rs";
    cout << reverseLetters(t, s) << "\n";
    
    getchar();
    return 0;
}

public static String reverse(String str){
	    	char[] arr = str.toCharArray();
	    	int start = 0;
	    	int end = arr.length-1;
	    	while(start<end){
	    		while( arr[start] >= '0' && arr[start] <= '9'){
	    			if( start == end)break;
	    			start++;
	    		}
	    		while( arr[end] >= '0' && arr[end] <= '9'){
	    			if( start == end)break;
	    			end--;
	    		}
	    		
	    		if(start<end){
		    		arr[start] ^= arr[end];
		    		arr[end] ^= arr[start];
		    		arr[start] ^= arr[end];
		    		start++;
		    		end--;
	    		}
	    	}
	    	
	    	return new String(arr);
	    }
	    public static void main(String[]args){
	    	///test cases
	    	String str = new String("str1ngw2thnumb3rs");
	    	System.out.println(" Input : str :" + str+ " Output = "+ reverse(str));
	    	System.out.println(" Input : str :" + "1111"+ " Output = "+ reverse("1111"));
	    	System.out.println(" Input : str :" + "1234a"+ " Output = "+ reverse("1234a"));
	    	System.out.println(" Input : str :" + "a1234"+ " Output = "+ reverse("a1234"));
	    	System.out.println(" Input : str :" + "abc1234"+ " Output = "+ reverse("abc1234"));
	    	System.out.println(" Input : str :" + "abcd1234"+ " Output = "+ reverse("abcd1234"));
	    	System.out.println(" Input : str :" + "abcd"+ " Output = "+ reverse("abcd"));
	    	System.out.println(" Input : str :" + ""+ " Output = "+ reverse(""));
	}

void reverseSpec(std::string& in, std::string &final)
{
    final = in; // this way digits stay in place
    std::string tmp;

    
    for (int i = in.length()-1, j = 0; i >= 0; i--)
    {
        // if it is alpha add it to our temp but reversed
        if (isdigit(final[j]))
            ++j;

        if (isalpha(in[i]) || isspace(in[i]))
        {
            final[j] = in[i];
            j++;
        }
        
    }
}


void testFancyRev()
{
    std::string input("vla1do1cavise3jp");
    std::string out;

    reverseSpec(input, out);

    std::cout << "in:  " << input << std::endl;
    std::cout << "out: " << out << std::endl;

}}

public static String reverse(String str){
		
		char ch[] = str.toCharArray();
		int start = 0;
		int end = str.length() -1;
		while(start<end){
			boolean isStartNum =Character.isDigit(ch[start]);
			boolean isEndNum =Character.isDigit(ch[end]);
			if(isStartNum) ++ start;
			if(isEndNum) -- end;
			if(!isStartNum && !isEndNum){
				char temp= ch[start];
				ch[start]=ch[end];
				ch[end]= temp;
				++start;
				--end;
			}
		}
		return String.valueOf(ch);
	}

A javascript solution

reverse = function(str){
	out = "";
	numbersArray = [];
	for(i=(str.length-1); i>-1; i--){
		if(parseInt(str[i]) == str[i]){
			numbersArray.push({num: str[i], pos: i});
		}else{
			out += str[i];
		}
	}
	numbersArray.forEach(function(val, index){
		console.log(val)
		pos = val.pos + index - 2
		out = [out.slice(0, pos), val.num, out.slice(pos)].join('');
	});
	return out;
}

/*
Write a function accepting a string with numbers and letters that reverses the
letters of the string but leave numbers in the same position.

Example input: str1ngw1thnumb3rs
Example output:srb1mun1htwgn3rts


*/
import java.util.*;
import java.lang.*;
class stringrevdemo
{
public static void main(String args[])
{
Scanner sc=new Scanner(System.in);
String s;
System.out.print("Enter the String:");
s=sc.next();
System.out.print("------------------\n");
System.out.println("Input:"+s);
char[] ch=new char[s.length()];
char[] ch1=new char[s.length()];
ch=s.toCharArray();
int j=0;
for(int i=s.length()-1;i>=0;i--)
{
if(Character.isDigit(ch[i]))
{
continue;
}
else
{
ch1[j]=ch[i];
j++;
}
}
j=0;
for(int i=0;i<s.length();i++)
{
if(Character.isDigit(ch[i]))
{
continue;
}
else
{
ch[i]=ch1[j];
j++;
}
}
System.out.print("Output:");
for(int i=0;i<s.length();i++)
{
System.out.print(ch[i]);
}
System.out.println();
}
}

Code not checked:

string reverseLettersOnly(string S){
	int start = 0, end = S.length()-1;
	while(start < end){
		while((start <S.length()) and (0 <= S[start] - '0') and (S[start] - '0' <=9)) start++;
		while((end  >=0) and (0 <= S[end] - '0') and (S[end] - '0' <=9)) end--;
		if (start <end) swap(S[start], S[end]);
		start++;
		end--;
	};
	return S;
};