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1 sections, 17 questions

Coding Problems

17 questions

Question 1

Find Second Largest

Problem

Find the second largest element in an array.

Solution

Code

#include <stdio.h>
#include <limits.h>

int secondLargest(int arr[], int n) {
    int first = INT_MIN, second = INT_MIN;
    for (int i = 0; i < n; i++) {
        if (arr[i] > first) {
            second = first;
            first = arr[i];
        } else if (arr[i] > second && arr[i] != first) {
            second = arr[i];
        }
    }
    return second;
}

Java

public int secondLargest(int[] arr) {
    int first = Integer.MIN_VALUE;
    int second = Integer.MIN_VALUE;
    for (int num : arr) {
        if (num > first) {
            second = first;
            first = num;
        } else if (num > second && num != first) {
            second = num;
        }
    }
    return second;
}

Python

def second_largest(arr):
    first = second = float('-inf')
    for num in arr:
        if num > first:
            second = first
            first = num
        elif num > second and num != first:
            second = num
    return second

Time: O(n)Space: O(1)

Question 2

Reverse Array

Problem

Reverse an array without using extra space.

Solution

Code

void reverseArray(int arr[], int n) {
    int start = 0, end = n - 1;
    while (start < end) {
        int temp = arr[start];
        arr[start] = arr[end];
        arr[end] = temp;
        start++;
        end--;
    }
}

Java

public void reverseArray(int[] arr) {
    int start = 0, end = arr.length - 1;
    while (start < end) {
        int temp = arr[start];
        arr[start] = arr[end];
        arr[end] = temp;
        start++;
        end--;
    }
}

Python

def reverse_array(arr):
    start, end = 0, len(arr) - 1
    while start < end:
        arr[start], arr[end] = arr[end], arr[start]
        start += 1
        end -= 1

Time: O(n)Space: O(1)

Question 3

Check Palindrome String

Problem

Check if a string is palindrome (case-insensitive).

Solution

Code

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

int isPalindrome(char str[]) {
    int left = 0, right = strlen(str) - 1;
    while (left < right) {
        if (tolower(str[left]) != tolower(str[right]))
            return 0;
        left++;
        right--;
    }
    return 1;
}

Java

public boolean isPalindrome(String str) {
    str = str.toLowerCase();
    int left = 0, right = str.length() - 1;
    while (left < right) {
        if (str.charAt(left) != str.charAt(right))
            return false;
        left++;
        right--;
    }
    return true;
}

Python

def is_palindrome(s):
    s = s.lower()
    left, right = 0, len(s) - 1
    while left < right:
        if s[left] != s[right]:
            return False
        left += 1
        right -= 1
    return True

Time: O(n)Space: O(1)

Question 4

Remove Duplicates

Problem

Remove duplicates from sorted array, return new length.

Solution

Code

int removeDuplicates(int arr[], int n) {
    if (n == 0) return 0;
    int j = 0;
    for (int i = 1; i < n; i++) {
        if (arr[i] != arr[j]) {
            j++;
            arr[j] = arr[i];
        }
    }
    return j + 1;
}

Java

public int removeDuplicates(int[] arr) {
    if (arr.length == 0) return 0;
    int j = 0;
    for (int i = 1; i < arr.length; i++) {
        if (arr[i] != arr[j]) {
            j++;
            arr[j] = arr[i];
        }
    }
    return j + 1;
}

Python

def remove_duplicates(arr):
    if not arr:
        return 0
    j = 0
    for i in range(1, len(arr)):
        if arr[i] != arr[j]:
            j += 1
            arr[j] = arr[i]
    return j + 1

Time: O(n)Space: O(1)

Question 5

Prime Number Check

Problem

Check if a number is prime.

Solution

Code

int isPrime(int n) {
    if (n <= 1) return 0;
    if (n <= 3) return 1;
    if (n % 2 == 0 || n % 3 == 0) return 0;
    for (int i = 5; i * i <= n; i += 6) {
        if (n % i == 0 || n % (i + 2) == 0)
            return 0;
    }
    return 1;
}

Java

public boolean isPrime(int n) {
    if (n <= 1) return false;
    if (n <= 3) return true;
    if (n % 2 == 0 || n % 3 == 0) return false;
    for (int i = 5; i * i <= n; i += 6) {
        if (n % i == 0 || n % (i + 2) == 0)
            return false;
    }
    return true;
}

Python

def is_prime(n):
    if n <= 1:
        return False
    if n <= 3:
        return True
    if n % 2 == 0 or n % 3 == 0:
        return False
    i = 5
    while i * i <= n:
        if n % i == 0 or n % (i + 2) == 0:
            return False
        i += 6
    return True

Time: O(√n)Space: O(1)

Question 6

GCD of Two Numbers

Problem

Find GCD (Greatest Common Divisor) of two numbers.

Solution

Code

int gcd(int a, int b) {
    if (b == 0) return a;
    return gcd(b, a % b);
}

Java

public int gcd(int a, int b) {
    if (b == 0) return a;
    return gcd(b, a % b);
}

Python

def gcd(a, b):
    if b == 0:
        return a
    return gcd(b, a % b)

Time: O(log(min(a,b)))Space: O(log(min(a,b)))

Question 7

Factorial

Problem

Find factorial of a number.

Solution

Code

long long factorial(int n) {
    if (n <= 1) return 1;
    return n * factorial(n - 1);
}

Java

public long factorial(int n) {
    if (n <= 1) return 1;
    return n * factorial(n - 1);
}

Python

def factorial(n):
    if n <= 1:
        return 1
    return n * factorial(n - 1)

Time: O(n)Space: O(n)

Question 8

Fibonacci Series

Problem

Print Fibonacci series up to n terms.

Solution

Code

void fibonacci(int n) {
    if (n <= 0) return;
    int a = 0, b = 1;
    printf("%d ", a);
    if (n > 1) printf("%d ", b);
    for (int i = 2; i < n; i++) {
        int c = a + b;
        printf("%d ", c);
        a = b;
        b = c;
    }
}

Java

public void fibonacci(int n) {
    if (n <= 0) return;
    int a = 0, b = 1;
    System.out.print(a + " ");
    if (n > 1) System.out.print(b + " ");
    for (int i = 2; i < n; i++) {
        int c = a + b;
        System.out.print(c + " ");
        a = b;
        b = c;
    }
}

Python

def fibonacci(n):
    if n <= 0:
        return
    a, b = 0, 1
    print(a, end=" ")
    if n > 1:
        print(b, end=" ")
    for i in range(2, n):
        c = a + b
        print(c, end=" ")
        a, b = b, c

Time: O(n)Space: O(1)

Question 9

Anagram Check

Problem

Check if two strings are anagrams.

Solution

Code

#include <string.h>
#include <stdlib.h>

int compare(const void *a, const void *b) {
    return *(char*)a - *(char*)b;
}

int isAnagram(char s1[], char s2[]) {
    int len1 = strlen(s1), len2 = strlen(s2);
    if (len1 != len2) return 0;
    qsort(s1, len1, sizeof(char), compare);
    qsort(s2, len2, sizeof(char), compare);
    return strcmp(s1, s2) == 0;
}

Java

public boolean isAnagram(String s1, String s2) {
    if (s1.length() != s2.length()) return false;
    char[] c1 = s1.toCharArray();
    char[] c2 = s2.toCharArray();
    Arrays.sort(c1);
    Arrays.sort(c2);
    return Arrays.equals(c1, c2);
}

Python

def is_anagram(s1, s2):
    if len(s1) != len(s2):
        return False
    return sorted(s1) == sorted(s2)

Time: O(n log n)Space: O(1)

Question 10

Reverse Words

Problem

Reverse words in a string.

Solution

Code

Java

public String reverseWords(String str) {
    String[] words = str.split(" ");
    StringBuilder result = new StringBuilder();
    for (int i = words.length - 1; i >= 0; i--) {
        result.append(words[i]);
        if (i > 0) result.append(" ");
    }
    return result.toString();
}

Python

def reverse_words(s):
    words = s.split()
    return ' '.join(reversed(words))

Time: O(n)Space: O(n)

Question 11

Count Vowels

Problem

Count vowels in a string.

Solution

Code

#include <ctype.h>

int countVowels(char str[]) {
    int count = 0;
    for (int i = 0; str[i] != '\0'; i++) {
        char c = tolower(str[i]);
        if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u')
            count++;
    }
    return count;
}

Java

public int countVowels(String str) {
    int count = 0;
    String vowels = "aeiouAEIOU";
    for (char c : str.toCharArray()) {
        if (vowels.indexOf(c) != -1)
            count++;
    }
    return count;
}

Python

def count_vowels(s):
    vowels = "aeiouAEIOU"
    return sum(1 for c in s if c in vowels)

Time: O(n)Space: O(1)

Question 12

Maximum Subarray Sum (Kadane's Algorithm)

Problem

Find maximum sum of contiguous subarray.

Solution

Code

int maxSubArraySum(int arr[], int n) {
    int max_sum = arr[0];
    int current_sum = arr[0];
    for (int i = 1; i < n; i++) {
        current_sum = (arr[i] > current_sum + arr[i]) ?
                     arr[i] : current_sum + arr[i];
        max_sum = (current_sum > max_sum) ? current_sum : max_sum;
    }
    return max_sum;
}

Java

public int maxSubArraySum(int[] arr) {
    int maxSum = arr[0];
    int currentSum = arr[0];
    for (int i = 1; i < arr.length; i++) {
        currentSum = Math.max(arr[i], currentSum + arr[i]);
        maxSum = Math.max(maxSum, currentSum);
    }
    return maxSum;
}

Python

def max_subarray_sum(arr):
    max_sum = current_sum = arr[0]
    for i in range(1, len(arr)):
        current_sum = max(arr[i], current_sum + arr[i])
        max_sum = max(max_sum, current_sum)
    return max_sum

Time: O(n)Space: O(1)

Question 13

Two Sum

Problem

Find two numbers that add up to target.

Solution

Code

Java

public int[] twoSum(int[] arr, int target) {
    Map<Integer, Integer> map = new HashMap<>();
    for (int i = 0; i < arr.length; i++) {
        int complement = target - arr[i];
        if (map.containsKey(complement)) {
            return new int[]{map.get(complement), i};
        }
        map.put(arr[i], i);
    }
    return new int[]{};
}

Python

def two_sum(arr, target):
    seen = {}
    for i, num in enumerate(arr):
        complement = target - num
        if complement in seen:
            return [seen[complement], i]
        seen[num] = i
    return []

Time: O(n)Space: O(n)

Question 14

Rotate Array

Problem

Rotate array to right by k positions.

Solution

Code

void reverse(int arr[], int start, int end) {
    while (start < end) {
        int temp = arr[start];
        arr[start] = arr[end];
        arr[end] = temp;
        start++;
        end--;
    }
}

void rotate(int arr[], int n, int k) {
    k = k % n;
    reverse(arr, 0, n - 1);
    reverse(arr, 0, k - 1);
    reverse(arr, k, n - 1);
}

Java

public void rotate(int[] arr, int k) {
    k = k % arr.length;
    reverse(arr, 0, arr.length - 1);
    reverse(arr, 0, k - 1);
    reverse(arr, k, arr.length - 1);
}

private void reverse(int[] arr, int start, int end) {
    while (start < end) {
        int temp = arr[start];
        arr[start] = arr[end];
        arr[end] = temp;
        start++;
        end--;
    }
}

Python

def rotate(arr, k):
    k = k % len(arr)
    arr.reverse()
    arr[:k] = reversed(arr[:k])
    arr[k:] = reversed(arr[k:])

Time: O(n)Space: O(1)

Question 15

Print Pyramid Pattern

Problem

Print pyramid pattern with n rows.

Solution

Number Problems

Code

void printPyramid(int n) {
    for (int i = 1; i <= n; i++) {
        // Print spaces
        for (int j = 1; j <= n - i; j++)
            printf(" ");
        // Print stars
        for (int j = 1; j <= 2 * i - 1; j++)
            printf("*");
        printf("\n");
    }
}

Python

def print_pyramid(n):
    for i in range(1, n + 1):
        print(" " * (n - i) + "*" * (2 * i - 1))

Question 16

Sum of Digits

Problem

Find sum of digits of a number.

Solution

Code

int sumOfDigits(int n) {
    int sum = 0;
    while (n > 0) {
        sum += n % 10;
        n /= 10;
    }
    return sum;
}

Python

def sum_of_digits(n):
    return sum(int(digit) for digit in str(n))

Question 17

Armstrong Number

Problem

Check if a number is Armstrong number.

Solution

Code

#include <math.h>

int isArmstrong(int n) {
    int original = n, sum = 0, digits = 0;
    // Count digits
    int temp = n;
    while (temp > 0) {
        digits++;
        temp /= 10;
    }
    // Calculate sum
    while (n > 0) {
        int digit = n % 10;
        sum += pow(digit, digits);
        n /= 10;
    }
    return sum == original;
}

Python

def is_armstrong(n):
    digits = len(str(n))
    return sum(int(d)**digits for d in str(n)) == n

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Infosys coding

Coding Problems

Find Second Largest

Problem

Solution

Code

Reverse Array

Problem

Solution

Code

Check Palindrome String

Problem

Solution

Code

Remove Duplicates

Problem

Solution

Code

Prime Number Check

Problem

Solution

Code

GCD of Two Numbers

Problem

Solution

Code

Factorial

Problem

Solution

Code

Fibonacci Series

Problem

Solution

Code

Anagram Check

Problem

Solution

Code

Reverse Words

Problem

Solution

Code

Count Vowels

Problem

Solution

Code

Maximum Subarray Sum (Kadane's Algorithm)

Problem

Solution

Code

Two Sum

Problem

Solution

Code

Rotate Array

Problem

Solution

Code

Print Pyramid Pattern

Problem

Solution

Number Problems

Code

Sum of Digits

Problem

Solution

Code

Armstrong Number

Problem

Solution

Code

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