GATE pattern drill

Practice set

Q1MCQ1 markPattern: pointer parameter

What does this print?

#include <stdio.h>
void f(int *p, int *q)
{
    p = q;
    *p = 2;
}

int main(void)
{
    int i = 0, j = 1;
    f(&i, &j);
    printf("%d %d\n", i, j);
    return 0;
}

• (A) 2 1
• (B) 2 2
• (C) 0 2
• (D) 0 1

Q2NAT2 marksPattern: recursion value

What does this print?

#include <stdio.h>
int f(int n)
{
    if (n == 0) return 0;
    return f(n / 2) * 10 + n % 2;
}

int main(void)
{
    printf("%d\n", f(13));
    return 0;
}

Numerical answer: ________

Q3NAT1 markPattern: loop count

What does this print?

#include <stdio.h>
int main(void)
{
    int i, j, c = 0;
    for (i = 1; i <= 16; i *= 2)
        for (j = 0; j < i; j++)
            c++;
    printf("%d\n", c);
    return 0;
}

Numerical answer: ________

Q4MCQ1 markPattern: scope

What does this print?

#include <stdio.h>
int x = 10;

void f(void)
{
    int x = 20;
    {
        int x = 30;
        printf("%d ", x);
    }
    printf("%d ", x);
}

int main(void)
{
    f();
    printf("%d\n", x);
    return 0;
}

• (A) 30 20 10
• (B) 30 30 30
• (C) 30 20 20
• (D) 10 20 30

Q5NAT2 marksPattern: tree code

What does this print?

#include <stdio.h>
#include <stdlib.h>
struct tnode {
    int data;
    struct tnode *left, *right;
};

struct tnode *insert(struct tnode *t, int x)
{
    if (t == NULL) {
        t = malloc(sizeof(struct tnode));
        t->data = x;
        t->left = t->right = NULL;
    } else if (x < t->data) t->left = insert(t->left, x);
    else t->right = insert(t->right, x);
    return t;
}

int h(struct tnode *t)
{
    int a, b;
    if (t == NULL) return -1;
    a = h(t->left);
    b = h(t->right);
    return (a > b ? a : b) + 1;
}

int main(void)
{
    int a[] = {8, 3, 10, 1, 6, 14, 4, 7, 13}, i;
    struct tnode *root = NULL;
    for (i = 0; i < 9; i++) root = insert(root, a[i]);
    printf("%d\n", h(root));
    return 0;
}

Numerical answer: ________

Q6NAT2 marksPattern: count structures

How many structurally different binary trees have 6 nodes?

Numerical answer: ________

Q7MCQ2 marksPattern: heap position

In a max-heap of 31 distinct keys (0-based), which index can NOT hold the 4th largest key?

• (A) 3
• (B) 1
• (C) 15
• (D) 7

Q8NAT1 markPattern: graph counting

What is the minimum number of edges in a simple graph with 25 vertices and 5 connected components?

Numerical answer: ________

Q9MCQ2 marksPattern: BST path

Which sequence can be the keys visited while searching a BST for 60?

• (A) 90 30 80 50 70 60
• (B) 20 90 30 85 95 60
• (C) 50 70 40 60
• (D) 90 30 80 50 40 60

Q10MSQ1 markPattern: UB spotting

Which statements have undefined behavior in C?

• (A) char *p = "ab"; p[0] = 'x';
• (B) i = i++ + 1;
• (C) int a[3]; a[2] = 5;
• (D) int *p = malloc(4); free(p); free(p);