CareerCup

@majia168 - are these actual FB interview questions? How many times are you interviewing at FB :) you have at least 5-6 a day.

Good questions though.

function letterSolver(str) {
	str = str.split(' ')
	
	numbers = str[0].split('')
	operation = str[1].split('')
	
	for (var i=0; i<operation.length; i++) {
		if (operation[i] !== "+" && operation[i] !== '-') {
			code = operation[i].charCodeAt() - 97
			operation[i] = numbers[code]
		}
	}
	
	console.log(operation)
	return eval(operation.join(''))
	
}


letterSolver("1234567 abc+efg")

Not sure if I got it right. We should substitute each letter with one digit in an equation like "123456=abc+efg", correct?

#include <stdio.h>
#include <string.h>
#include <ctype.h>

/*
* make a number starting at str[0] while characters starting at
* spc are alhpabets, store the operator if oper is not zero,
* also store the number of digits converted ijn nlen.
*/
int get_num(const char *str, const char *spc, int *nlen, char *oper)
{
	int num = 0, i = 0;
	while (*spc && isalpha(*spc)) {
		num = num * 10 + (str[i] - '0');
		++i;
		++spc;
	}

	if (oper && (*spc == '+' || *spc == '-')) {
		*oper = *spc;
	}

	*nlen = i;

	return num;
}


/*
* map the numeric part of the string to two numbers and do the specified
* arithmetic operation and return the result.
* NOTE: No validation is attempted: the numeric parts have to be of same
* length as the character string parts etc.
* The only validation is to check if the operator is + or -, if not returns
* -1.
*/
int do_map(const char *str, int len)
{

	char oper = 0;	

	int nstart = 0, nlen = 0;

	const char *spc = strchr(str, ' ');

	while (*spc && !isalpha(*spc))
		++spc;

	if (!spc || !*spc)
		return -1;

	int num1 = get_num(str, spc, &nlen, &oper);

	int add = 0, sub = 0;

	if (oper == '+')
		add = 1;
	else if (oper == '-')
		sub = 1;
	else
		return -1;

	// str starts at str + nlen, and alpla starts at spc + nlen + 1	
	int num2 = get_num(str + nlen, spc + nlen + 1, &nlen, 0);

	int res;

	if (add)
		res = num1 + num2;
	else
		res = num1 - num2;

	return res;
}

int main(int ac, const char *av[])
{
	if (!av[1]) {
		printf("Enter an expression string like \"1234567 abc+/-defg\"\n");
		return -1;
	}

	int res = do_map(av[1], strlen(av[1]));

	printf("str = %s, result = %d\n", av[1], res);

	return 0;
}

import java.util.*;

class StringToMath{
	public static void main(String... args){
		String s = "123456123 abc+efg+qer";
		
		int indexOf = s.indexOf(" ");

		StringBuilder b = new StringBuilder();

		Stack<String> operandStack = new Stack<>();
		Stack<Character> operatorStack = new Stack<>();

		int literalIndex = indexOf+1;
		for(int i=0;i<indexOf;i++){
			boolean isOperator  = isOperator(s,literalIndex);	
			
			if(isOperator){
					operatorStack.push(s.charAt(literalIndex));
					literalIndex++;
					operandStack.push(b.toString());
					b.delete(0,b.length());
			}
			b.append(s.charAt(i));
			literalIndex++;
		}
		if(b.length()!=0){
		operandStack.push(b.toString());
	}

		while(!operatorStack.isEmpty()){
			int num2 = Integer.parseInt(operandStack.pop());
			int num1 = Integer.parseInt(operandStack.pop());
			char operator = operatorStack.pop();
			operandStack.push(String.valueOf(getResult(num1,operator,num2)));
		}

		
		System.out.println(operandStack.pop());
	}


	public static boolean isOperator(String s, int ind){
		return s.charAt(ind)=='-' || s.charAt(ind) == '+';
	}

		public static int getResult(int num1,char operator,int num2){
				if(operator=='-'){
					num2 = num2- num1;
				}else{
					num2 = num2 + num1;
				}
				return num2;
		}

}

General solution for number of math operations:

package com.cracking.facebook;

public class CalculateMappedStringEquation {

	public final static String Equation = "1234567 abc+efg";
	
	public static void main(String[] args) {
		String translatedEquation = TranslateEquation(Equation);
		int result = CalculateEquation(translatedEquation);
		System.out.println("Input = " + Equation);
		System.out.println("Translated = " + translatedEquation);
		System.out.println("Result = " + result);
	}
	
	public static String TranslateEquation(String equation) {
		char[] values = equation.substring(0, equation.indexOf(" ")).toCharArray();
		char[] result = equation.substring(equation.indexOf(" ") + 1).toCharArray();

		for(int i=0, j=0; i<result.length; i++) {
			if( Character.isLetter(result[i]) ) {
				result[i] = values[j++];
			}
		}
		
		return new String(result);
	}
	
	public static int CalculateEquation(String equation) {
		int result = 0;
		int opIndex = IndexOfOperation(equation);
		int left = Integer.parseInt( equation.substring(0,opIndex) );
		int right = Integer.parseInt( equation.substring(opIndex+1) );
		
		char opChar = equation.charAt(opIndex);
		switch(opChar) {
			case '+':
				result = left + right;
				break;
			case '-':
				result = left - right;
				break;
			case '*':
				result = left * right;
				break;
			case '/':
				result = left / right;
				break;
			default:
				break;
		}
		
		return result;
	}
	
	public static int IndexOfOperation(String equation) {
		int i=0;
		while( Character.isDigit(equation.charAt(i)) ) {
			i++;
		}
		
		return i;
	}

}

Output:
Input = 1234567 abc+efg
Translated = 123+456
Result = 579

#include <stdio.h>

int parseandadd(char* str)
{
	int spc = 0;
	
	while(str[spc++] != ' ') { }
	
	int ch=spc, num1=0, num2=0, sum=0, numi=0, op=0;
	
	while(!(str[ch] == '+' || str[ch] == '-'))
	{
		num1 = (num1*10)+(str[numi++] - '0');
		++ch;
	}
	
	if(str[ch] == '-') op = 1;
	else if(str[ch] == '+') op = 0;
	else return -1;

	ch++;

	while(str[ch++] != '\0' && numi < spc)
	{
		num2 = (num2*10)+(str[numi++] - '0');
	}
	
	op?(sum = num1-num2):(sum = num1+num2);
	
	printf("%d %d = %d\n", num1, num2, sum);
	
	//scanf("%d", &spc);
	return sum;
}

int main()
{
	parseandadd("456123 abc+cde");
	return 0;
}

def string_add_sub(s):
  a = s.split()
  if len(a[1])-1 != len(a[0]):
    return 0
  
  for i in range(len(a[1])):
    
    if a[1][i] == "+":
      
      result = int(a[0][:i]) + int(a[0][i:])
    if a[1][i] == "-":
      result = int(a[0][:i]) - int(a[0][i:])
  
  return result

public class MappingNumber {
private static String givenString = "123456 abc+efg";

//Only two operations + or -

private static void mappingResult(String givenString){

String[] givenSplitArr = givenString.split(" ");
String numberString = givenSplitArr[0];
String operatorString = givenSplitArr[1];

if(!operatorString.contains("+") && !operatorString.contains("-")){
System.out.println("No Operator exists");
return;
}

int i =0;
int j =0;
String operand1="", operand2 = "";
boolean isOPeratorFound = false;
while(i<numberString.length() && j<operatorString.length()){

if(operatorString.charAt(j)!='+' && operatorString.charAt(j)!='-'){
if(!isOPeratorFound)
operand1 = operand1+numberString.charAt(i);
else
operand2 = operand2+numberString.charAt(i);
i++;
}else{
isOPeratorFound = true;
}
j++;
}

System.out.println(Integer.parseInt(operand1)+Integer.parseInt(operand2));
}

public static void main(String[] args) {
mappingResult(givenString);
}

}

public class MappingNumber {
	private static String givenString = "123456 abc+efg";

	//Only two operations + or -

	private static void mappingResult(String givenString){

		String[] givenSplitArr = givenString.split(" ");
		String numberString = givenSplitArr[0];
		String operatorString = givenSplitArr[1];

		if(!operatorString.contains("+") && !operatorString.contains("-")){
			System.out.println("No Operator exists");
			return;
		}

		int i =0;
		int j =0;
		String operand1="", operand2 = "";
		boolean isOPeratorFound = false;
		while(i<numberString.length() && j<operatorString.length()){

			if(operatorString.charAt(j)!='+' && operatorString.charAt(j)!='-'){
				if(!isOPeratorFound)
					operand1 = operand1+numberString.charAt(i);
				else
					operand2 = operand2+numberString.charAt(i);	
				i++;
			}else{
				isOPeratorFound = true;
			}
			j++;
		}

		System.out.println(Integer.parseInt(operand1)+Integer.parseInt(operand2));
	}

	public static void main(String[] args) {
		mappingResult(givenString);
	}

}

func getSolution(s string) int64 {
	spaceIndex := 0
	operatorIndex := 0
	for s[spaceIndex] != ' ' {
		spaceIndex += 1
	}

	var operator = SUM

	i := spaceIndex + 1
	for s[i] != SUM && s[i] != SUB {
		i += 1
	}
	operatorIndex = i

	if s[i] == SUB {
		operator = SUB
		i += 1
	}

	op1, _ := strconv.ParseInt(s[:operatorIndex-spaceIndex-1], 10, 64)
	op2, _ := strconv.ParseInt(s[operatorIndex-spaceIndex-1:spaceIndex], 10, 64)

	if operator == SUM {
		return op1 + op2
	}
	return op1 - op2
}

func getSolution(s string) int64 {
	spaceIndex := 0
	operatorIndex := 0
	for s[spaceIndex] != ' ' {
		spaceIndex += 1
	}

	var operator = SUM

	i := spaceIndex + 1
	for s[i] != SUM && s[i] != SUB {
		i += 1
	}
	operatorIndex = i

	if s[i] == SUB {
		operator = SUB
		i += 1
	}

	op1, _ := strconv.ParseInt(s[:operatorIndex-spaceIndex-1], 10, 64)
	op2, _ := strconv.ParseInt(s[operatorIndex-spaceIndex-1:spaceIndex], 10, 64)

	if operator == SUM {
		return op1 + op2
	}
	return op1 - op2
}