Geeks for Geeks — Questions and Solution (Practice/School) — 1
Sum of Series
Sum of Series | Practice | GeeksforGeeks
Write a program to find the sum of the given series 1+2+3+ . . . . . .(N terms) Example 1: Input: N = 1 Output: 1…
class Solution {
public:
long long seriesSum(int n) {
// code here
long long n1 = n;
return (n1*(n1+1))/2;
}
};
Find the median
Find the median | Practice | GeeksforGeeks
Given an array arr[] of N integers, calculate the median. NOTE: Return the floor value of the median. Example 1: Input…
class Solution
{
public:
public:
int find_median(vector<int> v)
{
// Code here.
sort(v.begin(),v.end());
int l = v.size();
if(l%2==0){
return (v[(l/2)-1]+v[(l/2)])/2;
}
else {
return v[l/2];
}
}
};
Check for Binary
Check for Binary | Practice | GeeksforGeeks
Given a non-empty sequence of characters str, return true if sequence is Binary, else return false Example 1: Input…
#include <bits/stdc++.h>
using namespace std;
bool isBinary(string str);
// Driver program to test above functions
int main()
{
string str;
int t;
scanf("%d\n", &t);
while (t--)
{
cin >> str;
cout << isBinary(str) << endl;
}
return 0;
}
// } Driver Code Ends
// Return true if str is binary, else false
bool isBinary(string str)
{
// Your code here
for(int i=0;i<str.size();i++){
if (str[i] != '0' && str[i] != '1')
return false;
}
return true;
}
Sum of Array
Sum of Array | Practice | GeeksforGeeks
Given an integer array arr[] of size n. The task is to find sum of it. Example 1: Input: n = 4 arr[] = {1, 2, 3, 4}…
class Solution {
int sum(int arr[], int n) {
// code here
int total=0;
for(int i=0;i<n;i++)
total += arr[i];
return total;
}
}
Print Elements of Array
Print Elements of Array | Practice | GeeksforGeeks
Given an array arr of size n, print all its elements space-separated. Note: You don't need to move to the next line…
class Solution{
public:
//Just print the space seperated array elements
void printArray(int arr[], int n) {
// code here
for(int i=0;i<n;i++)
cout<<arr[i]<<" ";
}
};
Find Index
Find Index | Practice | GeeksforGeeks
Given an unsorted array arr[] of n integers and a key which is present in this array. You need to write a program to…
class Solution
{
public:
vector<int> findIndex(int arr[], int n, int key)
{
//code here.
vector <int>v1;
for(int i=0;i<n;i++)
{
if (arr[i] == key){
v1.push_back(i); break;
}
}
for(int i=n;i>=0;i--)
{
if (arr[i] == key){
v1.push_back(i); break;}
}
if (v1.size() == 0 )
return {-1,-1};
return v1;
}
};
Palindrome
Palindrome | Practice | GeeksforGeeks
Given an integer, check whether it is a palindrome or not. Note : Strings which read the same backwards as forwards …
class Solution
{
public:
string is_palindrome(int n)
{
// Code here.
int rev = 0;
int n1 = n;
while(n != 0)
{
rev = rev *10 + (n %10);
n = n /10;
}
if (rev == n1)
return "Yes";
else
return "No";
}
};
Reverse digits
Reverse digits | Practice | GeeksforGeeks
You are given an integer N, reverse the digits of given number N, ensuring that the reversed number has no leading…
class Solution
{
public:
long long int reverse_digit(long long int n)
{
long long int rev = 0;
int n1 = n;
while(n != 0)
{
rev = rev *10 + (n %10);
n = n /10;
}
return rev;
}
};
GCD of two numbers
GCD of two numbers | Practice | GeeksforGeeks
Given two positive integers a and b, find GCD of a and b.
class Solution {
public:
int gcd(int a, int b) {
while(a != b){
if( a > b){
a = a - b;
}
else{
b = b - a;
}
}
return a;
}
};
Another Approach
class Solution {
public:
int gcd(int a, int b) {
if( b == 0){
return a;
}
return gcd(b, a % b);
}
};
Swap kth elements
Swap kth elements | Practice | GeeksforGeeks
Given an array arr of size n, swap the kth element from the beginning with kth element from the end.
class Solution {
public:
void swapKth(int n, int k, vector<int> &arr) {
int temp = arr[k-1];
arr[k-1] = arr[n-k];
arr[n-k] = temp;
}
};
Convert String to LowerCase
Convert String to LowerCase | Practice | GeeksforGeeks
Given a string s. The task is to convert characters of string to lowercase. Example 1: Input: s = "ABCddE" Output…
class Solution {
public:
string toLower(string s) {
// string str = "";
for(int i=0;i<s.size();i++)
s[i] = tolower(s[i]);
return s;
}
};
Remove Spaces
Remove Spaces | Practice | GeeksforGeeks
Given a string, remove spaces from it. Example 1: Input: S = "geeks for geeks" Output: geeksforgeeks Explanation: All…
class Solution
{
public:
string modify (string s)
{
//code here.
string s1 ="";
for(int i=0;i<s.size();i++)
{
if(s[i] != ' ')
s1 = s1 + s[i];
}
return s1;
}
};
C++ Array (print an element) | Set 2
C++ Array (print an element) | Set 2 | Practice | GeeksforGeeks
Given an array arr of n integers and an index key(0-based index). Your task is to return the element present at the…
class Solution {
public:
int findElementAtIndex(int n, int key, vector<int> &arr) {
// code here
return arr[key];
}
};
if-else (Decision Making)
if-else (Decision Making) | Practice | GeeksforGeeks
Given two integers, n and m. The task is to check the relation between n and m. Example 1: Input: n = 4 m = 8 Output…
class Solution {
public:
string compareNM(int n, int m){
// code here
if (n < m)
return "lesser";
else if (n > m)
return "greater";
else
return "equal";
}
};
Perfect Arrays
Perfect Arrays | Practice | GeeksforGeeks
Given an array arr of size n and you have to tell whether the arr is perfect or not. An array is said to be perfect if…
class Solution {
public:
bool isPerfect(int n, vector<int> &arr) {
// code here
for(int i=0, j=arr.size()-1; i<j;i++,j--)
{
if (arr[i] != arr[j])
return false;
}
return true;
}
};
Odd or Even
Odd or Even | Practice | GeeksforGeeks
Given a positive integer N, determine whether it is odd or even. Example 1: Input: N = 1 Output: odd Explanation: The…
class Solution{
public:
string oddEven(int N){
// code here
if(N % 2 ==0)
return "even";
else
return "odd";
}
};