Uber Interview Question for Senior Software Development Engineers


Country: India
Interview Type: Phone Interview




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of 0 vote

import java.util.*;

public class ValidParentheses {


    public static void main(String[] args) {

        final Map<Integer, List<String>> cache = new HashMap<>();
        long start= System.currentTimeMillis();
        List<String> result = new ValidParentheses().generate(11, cache);
        long end  = System.currentTimeMillis();

        for (String s : result) {
            System.out.println(s);
        }
        System.out.println(result.size());
        System.out.printf("Total ms elapsed " + (end- start));
    }


    public List<String> generate(int n, Map<Integer, List<String>> cache) {
        if (cache.containsKey(n)) {
            System.out.printf("expression for i=%d requested & found in cache%n", n);
            return cache.get(n);
        } else {
            System.out.printf("expression for i=%d requested & NOT found in cache%n", n);
        }
        if (n == 0) {
            List<String> list = new ArrayList<>(Arrays.asList(""));
            cache.put(n, list);
            return list;
        }

        if (n == 1) {
            List<String> list = new ArrayList<>(Arrays.asList("()"));
            cache.put(n, list);
            return list;
        }

        if (n == 2) {
            List<String> list = new ArrayList<>(Arrays.asList("()()", "(())"));
            cache.put(n, list);
            return list;
        }

        // for n=3 or above, let this method calculate and cache
        List<String> result = new ArrayList<>();

        for (int i = 0; i < n; ++i)
            for (String in : generate(i, cache))
                for (String out : generate(n - 1 - i, cache))
                    result.add("(" + in + ")" + out);

        cache.put(n, result);
        return result;
    }
}

- Makarand August 20, 2017 | Flag Reply
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of 0 vote

#include<bits/stdc++.h>
using namespace std;
typedef long long int int64;
void paren(int64 n, int64 m , string s){
	if(m==0) {
		cout<<s<<endl;
		return ;
	}
	if(n>0) {
		s.append("{");
		paren( n -1 , m , s );
		s.pop_back();
	}
	if(n<m){
		s.append("}");
		paren( n , m - 1 , s );
		s.pop_back();
	}
}
int main(){
	int64 n;
	cin>>n;
	paren( n , n , "");
}

- shashanksi2009 September 20, 2017 | Flag Reply
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of 0 vote

def fun(i,closed,ar,n):
    if i==2*n:
        print(ar)
        return
    op=i-closed;
    if(closed<n):
        fun(i+1,closed+1,ar+'(',n)
    if(op<closed):
        fun(i+1,closed,ar+')',n)

- raj April 12, 2018 | Flag Reply
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0
of 0 vote

def fun(i,closed,ar,n):
    if i==2*n:
        print(ar)
        return
    op=i-closed;
    if(closed<n):
        fun(i+1,closed+1,ar+'(',n)
    if(op<closed):
        fun(i+1,closed,ar+')',n)

- raj April 12, 2018 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

public class Parenthesis {

	static void pp(int lL, int rL, int pos, char[] str){
		if(lL < 0 || lL > rL)
			return;
		
		if((lL==rL && rL==0)){
			System.out.println(str);
			return;
		}
		
		if(pos >= str.length)
			return;
		
		str[pos] = '(';
		pp(lL-1, rL, pos+1, str);
		str[pos] = ')';
		pp(lL, rL-1, pos+1, str);
	}
	
	public static void main(String[] args) {
		int n = 9;
		int pairs = n/2;
		char[] str = new char[pairs*2];
		pp(pairs, pairs, 0, str);
	}

}

- lareinev May 07, 2018 | Flag Reply


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