Societe Generale interview prep

DSAMedium

You reverse a singly linked list in place by walking it once with three pointers, prev, curr and next. At each node, what do you do?

1. Save next = curr.next, point curr.next at prev, then move prev to curr and curr to next
2. Swap the node's value with the value at the other end of the list
3. Push every node onto a stack, then pop them all
4. Point curr.next at curr.next.next

This topic is named in a candidate’s interview report: On-campus interview, 2022, on GeeksforGeeks.

DSAMedium

In this grid, 1 is land and 0 is water, and land joins up, down, left and right. How many islands are there?

1 1 0 0
0 1 0 1
1 0 0 1
0 0 1 0

1. 3
2. 5
3. 4
4. 2

This topic is named in a candidate’s interview report: SDE on-campus interview, 2021, on GeeksforGeeks.

DSAMedium

You build a stack from two queues. push(x) enqueues x into the empty queue q2, moves every element of q1 behind it, then swaps the names of q1 and q2. What do push and pop cost?

1. O(n) push and O(1) pop
2. O(1) and O(1)
3. O(1) push and O(n) pop
4. O(log n) each

This topic is named in a candidate’s interview report: Intern and full-time on-campus interview, 2022, on GeeksforGeeks.

DSAHard

What is the best known time to find the median of two sorted arrays of sizes m and n?

1. O(m + n), by merging
2. O((m + n) log(m + n)), by sorting
3. O(log(min(m, n))), by binary searching the cut in the smaller array
4. O(m * n)

This topic is named in a candidate’s interview report: SDE on-campus interview, 2021, on GeeksforGeeks.

JavaHard

What does this print?

public class Main {
    public static void main(String[] args) {
        Integer a = 127, b = 127;
        Integer c = 128, d = 128;
        int e = 128;
        System.out.println((a == b) + " " + (c == d) + " " + (c == e));
    }
}

1. true true true
2. true false false
3. false false true
4. true false true

This topic is named in a candidate’s interview report: Global Solutions Centre on-campus interview, 2020, on GeeksforGeeks.

PythonEasy

What does this print?

def down(n):
    if n == 0:
        return
    print(n, end=" ")
    down(n - 1)

def up(n):
    if n == 0:
        return
    up(n - 1)
    print(n, end=" ")

down(3)
print("|", end=" ")
up(3)

1. 3 2 1 | 3 2 1
2. 1 2 3 | 1 2 3
3. 1 2 3 | 3 2 1
4. 3 2 1 | 1 2 3

This topic is named in a candidate’s interview report: Global Solutions Centre on-campus interview, 2020, on GeeksforGeeks.

C and C++Hard

Why should a base class that is used polymorphically have a virtual destructor?

1. Deleting a derived object through a base pointer is otherwise undefined behaviour, and the derived destructor usually never runs
2. Without it, the class cannot be instantiated
3. It makes destruction faster
4. Virtual destructors are needed for any class that has a constructor

This topic is named in a candidate’s interview report: On-campus interview, 2022, on GeeksforGeeks.

C and C++Medium

You wrote an integer stack class in C++ and now need the same stack for strings and doubles. What is the idiomatic change?

1. Copy the class once for each type
2. Make it a class template, template <typename T> class Stack, storing T values
3. Store everything as void* and cast
4. Use a macro to rename int

This topic is named in a candidate’s interview report: SDE on-campus interview, Bangalore, 2023, on LeetCode.

C and C++Medium

What does this print?

#include <iostream>
#include <stdexcept>
#include <vector>

class IntStack {
    std::vector<int> v;
public:
    void push(int x) { v.push_back(x); }
    int pop() {
        if (v.empty()) throw std::underflow_error("empty");
        int x = v.back();
        v.pop_back();
        return x;
    }
};

int main() {
    IntStack s;
    s.push(7);
    try {
        std::cout << s.pop() << " ";
        std::cout << s.pop() << " ";
    } catch (const std::underflow_error& e) {
        std::cout << e.what();
    }
}

1. 7 0
2. 7 empty
3. 7 7
4. empty

This topic is named in a candidate’s interview report: SDE on-campus interview, Bangalore, 2023, on LeetCode.

C and C++Medium

A C++ function throws an exception and no catch block anywhere up the call stack matches its type. What happens?

1. std::terminate is called, which by default aborts the program
2. The exception is ignored and the program continues
3. The compiler refuses to build the program
4. The function returns 0

This topic is named in a candidate’s interview report: On-campus interview, 2022, on GeeksforGeeks.

C and C++Medium

What does this print?

#include <iostream>

struct Tag {
    char c;
    Tag(char x) : c(x) { std::cout << c << "+ "; }
    ~Tag() { std::cout << c << "- "; }
};

int main() {
    Tag a('A');
    {
        Tag b('B');
    }
    Tag c('C');
}

1. A+ B+ C+ A- B- C-
2. A+ B+ C+ C- B- A-
3. A+ B+ B- C+ C- A-
4. A+ B+ B- C+ A- C-

This topic is named in a candidate’s interview report: On-campus interview, 2022, on GeeksforGeeks.

DBMS and SQLMedium

Which query returns the second-highest salary in emp?

1. SELECT MAX(salary) FROM emp WHERE salary < (SELECT MAX(salary) FROM emp);
2. SELECT salary FROM emp ORDER BY salary LIMIT 2;
3. SELECT MAX(salary) - 1 FROM emp;
4. SELECT SECOND(salary) FROM emp;

This topic is named in a candidate’s interview report: On-campus interview, 2022, on GeeksforGeeks.

DBMS and SQLMedium

Inside one transaction you insert row A, run SAVEPOINT s1, insert row B, then run ROLLBACK TO SAVEPOINT s1 and COMMIT. Which rows are saved?

1. Neither A nor B
2. Only B
3. Only A
4. Both A and B

This topic is named in a candidate’s interview report: SDE on-campus interview, Bangalore, 2023, on LeetCode.

Web developmentEasy

After a release, some users say a page shows two of its three new buttons, while it looks right for you. What is the most likely cause?

1. The server is down for those users
2. Their screens are too small
3. Their browser or a CDN is serving the old cached JavaScript or CSS next to the new HTML; versioned asset URLs (app.js?v=2 or a content hash) prevent it
4. The database lost the third button

This topic is named in a candidate’s interview report: Software engineer on-campus interview, 2024, on GeeksforGeeks.

AptitudeMedium

"The day before yesterday I was 21, and next year I will turn 24." On which day can this be true?

1. Only on 1 January, for someone born on 31 December
2. Only on a birthday
3. Only in a leap year
4. It can never be true

This topic is named in a candidate’s interview report: Software engineer on-campus interview, 2024, on GeeksforGeeks.