C Programming Language || Hands On Coding

🚀 HandsOnC – 60 Day Challenge begins on 24 August 2026. If you're a beginner and want to learn C the right way, you're in the right place. 📅 Challenge Starts: 24 August 2026 Invite your classmates or friends who are learning C and begin the HandsOnC – 60 Day Challenge together on 24 August. Link: https://t.me/c_programming_language_coding See you on 24 August! 🚀

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Leetcode 283: https://leetcode.com/problems/move-zeroes/ class Solution { public: void moveZeroes(vector<int>& nums) { if (nums.size() < 2) { return; } int leftIdx = 0, rightIdx = 1; while (rightIdx < nums.size()) { if (nums[leftIdx] != 0) { leftIdx++; rightIdx++; } else if (nums[rightIdx] == 0) { rightIdx++; } else { swap(nums[leftIdx], nums[rightIdx]); } } } };

Leetcode 66: https://leetcode.com/problems/plus-one/ class Solution { public: std::vector<int> plusOne(std::vector<int>& digits) { int currentIndex = digits.size() - 1; while (digits[currentIndex] == 9) { if (currentIndex == 0) { std::vector<int> resultArr(digits.size() + 1, 0); resultArr[0] = 1; return resultArr; } digits[currentIndex] = 0; currentIndex--; } digits[currentIndex]++; return digits; } };

Leetcode 350: https://leetcode.com/problems/intersection-of-two-arrays-ii/ class Solution { public: std::vector<int> intersect(std::vector<int>& nums1, std::vector<int>& nums2) { std::unordered_map<int, int> numsMap; std::vector<int> intersectedNums; for (int num : nums1) { numsMap[num]++; } for (int num : nums2) { if (numsMap.find(num) != numsMap.end() && numsMap[num] > 0) { intersectedNums.push_back(num); numsMap[num]--; if (numsMap[num] == 0) { numsMap.erase(num); } } } return intersectedNums; } };

Leetcode 136: https://leetcode.com/problems/single-number/ class Solution { public: int singleNumber(vector<int>& nums) { int finder = 0; for(int i = 0; i < nums.size(); i++) { finder = finder ^ nums[i]; } return finder; } };

Leetcode 217: https://leetcode.com/problems/contains-duplicate/description/ #include <vector> #include <algorithm> class Solution { public: bool containsDuplicate(std::vector<int>& nums) { std::sort(nums.begin(), nums.end()); for (size_t i = 0; i < nums.size() - 1; i++) { if (nums[i] == nums[i + 1]) { return true; } } return false; } };

Leetcode 189: https://leetcode.com/problems/rotate-array/ #include <vector> #include <iostream> class Solution { public: void rotate(std::vector<int>& nums, int k) { k = k % nums.size(); // Reversing the whole array reverseNumsArr(nums, 0, nums.size()); // Reversing first k elements reverseNumsArr(nums, 0, k); // Reversing remaining elements reverseNumsArr(nums, k, nums.size()); } private: void reverseNumsArr(std::vector<int>& nums, int start, int end) { end--; // Adjusting end to be the last index while (start < end) { std::swap(nums[start], nums[end]); start++; end--; } } };

Leetcode 122: https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/ class Solution { public: int maxProfit(vector<int>& prices) { int maxProfit = 0; for(int i = 0; i < prices.size() - 1; i++) { if(prices[i] < prices[i + 1]) { int diff = prices[i + 1] - prices[i]; maxProfit += diff; } } return maxProfit; } };

Leetcode 26: https://leetcode.com/problems/remove-duplicates-from-sorted-array/description/ class Solution { public: int removeDuplicates(vector<int>& nums) { int lastUniqueElementIdx = 0; for (int i = 1; i < nums.size(); i++) { if (nums[lastUniqueElementIdx] != nums[i]) { nums[lastUniqueElementIdx + 1] = nums[i]; lastUniqueElementIdx++; } } return lastUniqueElementIdx + 1; } };

Program: Searching in a 2D array. #include <iostream> using namespace std; int* search(int arr[][3], int rows, int cols, int target) { static int result[2]; result[0] = -1; result[1] = -1; for (int i = 0; i < rows; i++) { for (int j = 0; j < cols; j++) { if (arr[i][j] == target) { result[0] = i; result[1] = j; return result; } } } return result; } int main() { int arr[3][3] = { {20, 45, 10}, {32, 26, 22}, {47, 98, 37} }; int target; cout << "Enter target element: "; cin >> target; int* result = search(arr, 3, 3, target); if (result[0] != -1) { cout << "Element found at index (" << result[0] << "," << result[1] << ")" << endl; } else { cout << "Element not found" << endl; } return 0; } #linearsearch

Program: Finding maximum element from an array. #include <iostream> using namespace std; int findMax(int arr[], int size) { int max = arr[0]; for (int i = 1; i < size; i++) { if (arr[i] > max) { max = arr[i]; } } return max; } int main() { int arr[] = {12, 32, 23, 11, 39}; int size = sizeof(arr) / sizeof(arr[0]); int maxNumber = findMax(arr, size); cout << "Maximum number in array: " << maxNumber << endl; return 0; }

Program: Finding minimum element in an array. #include <iostream> using namespace std; int findMin(int arr[], int size) { int min = arr[0]; for (int i = 1; i < size; i++) { if (arr[i] < min) { min = arr[i]; } } return min; } int main() { int arr[] = {12, 32, 23, 11, 39}; int size = sizeof(arr) / sizeof(arr[0]); int minNumber = findMin(arr, size); cout << "Minimum number in array: " << minNumber << endl; return 0; }

Program: Searching for a character in specified range. #include <iostream> #include <string> using namespace std; int searchInStr(const string &str, char ch, int start, int end) { for (int i = start; i <= end; i++) { if (str[i] == ch) { return i; } } return -1; } int main() { string str = "Java Programming"; char ch; int start, end; cout << "Enter character to search: "; cin >> ch; cout << "Enter the range,\n"; cout << "Enter the start index: "; cin >> start; cout << "Enter the end index: "; cin >> end; int res = searchInStr(str, ch, start, end); if (res == -1) { cout << "Character not found in the specified range" << endl; } else { cout << "Character is at index " << res << endl; } return 0; }

Program: Searching for first occurrence of a character in a string. #include <iostream> using namespace std; int searchInStr(string str, char ch) { for (int i = 0; i < str.length(); i++) { if (str[i] == ch) { return i; } } return -1; } int main() { string str = "Java Programming"; char ch; cout << "Enter character to search: "; cin >> ch; int res = searchInStr(str, ch); if (res == -1) { cout << "Character not found in the String" << endl; } else { cout << "Character is at index " << res << endl; } return 0; }

Program: Reversing of an Array. #include <iostream> #include <vector> using namespace std; void reverseArray(vector<int>& arr) { int n = arr.size(); for (int i = 0; i < n / 2; i++) { swap(arr[i], arr[n - 1 - i]); } } int main() { vector<int> arr = {1, 2, 3, 4, 5, 6}; reverseArray(arr); for (size_t i = 0; i < arr.size(); i++) { cout << arr[i] << " "; } cout << endl; return 0; }

Program : Finding Maximum element in an Array. #include <iostream> using namespace std; int findMax(int arr[], int size) { int maxElem = arr[0]; for(int i = 1; i < size; i++) { if(maxElem < arr[i]) { maxElem = arr[i]; } } return maxElem; } int main() { int arr[] = {10, 5, 1, 3, 6}; int size = sizeof(arr) / sizeof(arr[0]); int maxElem = findMax(arr, size); cout << "Maximum Element : " << maxElem << endl; return 0; }

Program : Armstrong or Not #include <iostream> #include <cmath> using namespace std; bool isArmstrong(int num) { int originalNum = num, sum = 0, digits = to_string(num).length(); while (num > 0) { int rem = num % 10; sum += pow(rem, digits); num /= 10; } return originalNum == sum; } int main() { int num; cout << "Enter any number: "; cin >> num; if (isArmstrong(num)) { cout << num << " is an Armstrong number." << endl; } else { cout << num << " is not an Armstrong number." << endl; } return 0; }

Program : Prime or Not #include <iostream> using namespace std; bool isPrime(int num) { if (num < 2) { return false; } for (int i = 2; i * i <= num; i++) { if (num % i == 0) { return false; } } return true; } int main() { int num; cout << "Enter any number: "; cin >> num; if (isPrime(num)) { cout << num << " is a prime number" << endl; } else { cout << num << " is not a prime number" << endl; } return 0; }

Program: Reversing of a number. #include <iostream> using namespace std; int reverseNumber(int num) { int reversedNum = 0; while (num > 0) { int rem = num % 10; reversedNum = reversedNum * 10 + rem; num /= 10; } return reversedNum; } int main() { int num; cout << "Enter the number to reverse: "; cin >> num; int reversedNum = reverseNumber(num); cout << "Reverse of " << num << " is " << reversedNum << endl; return 0; }