C++ Tutorials

2D Array basic input and output

#include<bits/stdc++.h>
#include<cstring>
#include<iostream>
using namespace std;

int main(){

//2D array
int row, col;
cout<<"Enter no of row: ";
cin>>row;
cout<<"Enter no of column: ";
cin>>col;
int arr[row][col];

//Input 2D array
for(int i=0; i<row; i++){
  for(int j=0; j<col; j++){
    cin>>arr[i][j];
  }
}

//Output 2D array
for(int i=0; i<row; i++){
  for(int j=0; j<col; j++){
    cout<<arr[i][j];
  }
  cout<<endl;
}

return 0 ;
}

2D Array Searching a Matrix

#include<bits/stdc++.h>
#include<cstring>
#include<iostream>
using namespace std;

int main(){

//2D array
int row, col;
cout<<"Enter no of row: ";
cin>>row;
cout<<"Enter no of column: ";
cin>>col;
int arr[row][col];

//Input 2D array
for(int i=0; i<row; i++){
  for(int j=0; j<col; j++){
    cin>>arr[i][j];
  }
}

//Output 2D array
for(int i=0; i<row; i++){
  for(int j=0; j<col; j++){
    cout<<arr[i][j];
  }
  cout<<endl;
}
//Search in Matrix

int x;
cout<<"Search any no in a matrix: ";
cin>>x;
bool flag=false;
for(int i=0; i<row; i++){
  for(int j=0; j<col; j++){
    if(arr[i][j]==x){
      cout<<i<<" "<<j<<" "<<endl;
      flag=true;
    }
  }
}
if(flag){
  cout<<"Element is found: "<<endl;
}
else{
  cout<<"Element not found: "<<endl;
}

return 0 ;
}

2D Array Spiral Order Matrix Traversal in C++

#include<bits/stdc++.h>
#include<cstring>
#include<iostream>
using namespace std;

int main(){

//2D array
int row, col;
cout<<"Enter no of row: ";
cin>>row;
cout<<"Enter no of column: ";
cin>>col;
int arr[row][col];

//Input 2D array
for(int i=0; i<row; i++){
  for(int j=0; j<col; j++){
    cin>>arr[i][j];
  }
}
//Spiral order print
int rowStart=0, rowEnd=row-1, colStart=0, colEnd=col-1;
while(rowStart <= rowEnd && colStart <= colEnd){
  //for Row Start
  for(int col = colStart; col <=colEnd; col++){
    cout<<arr[rowStart][col]<<" ";
  }
  rowStart++;
  //for column end
  for(int row = rowStart; row<=rowEnd; row++){
    cout<<arr[row][colEnd]<<" ";
    colEnd--;
    //for row end
    for(int col= colEnd; col>=colStart; col--){
      cout<<arr[rowEnd][col]<<" ";
      rowEnd--;
      //for column Start
      for(int row = rowEnd; row >= rowStart; row--){
        cout<<arr[row][colStart]<<" ";
      }
      colStart++;
    }
  }
}

return 0 ;
}

2D Array Wave Print (Traversal) in C++

#include<iostream>
using namespace std;
int main(){
  int n, m;
  cout<<"Enter Row: ";
  cin>>m;
  cout<<"Enter column: ";
  cin>>n;
int arr[n][m];
if((m>=1 && m<=10)&&((n>=1 && n<=10)))
{
for(int i=0;i<m;i++)
{
	for(int j=0;j<n;j++)
	{
		cin>>arr[i][j];
	}
}
for(int j=0;j<n;j=j+1)
{
if(j%2==0)
{
	for(int i=0;i<m;i++)
		{
			cout<<arr[i][j]<<","<<endl;
		}
}
else
{
	for(int i=m-1;i>=0;i--)
	{
		cout<<arr[i][j]<<",";
	}
}
}
}
cout<<"END";
}

2D Array Rotate image NxN array 90 degree in C++

#include<iostream>
using namespace std;
void rotate(int ar[][5],int n)
{
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            if(i<j)
            {
                swap(ar[i][j],ar[j][i]);
            }
        }
    }
}
int main() 
{
   int ar[5][5];
   int n;
   cin>>n;
   for(int i=0;i<n;i++)
   {
       for(int j=0;j<n;j++)
       {
           cin>>ar[i][j];
       }
   }
   rotate(ar,n);
   for(int i=n-1;i>=0;i--)
   {
       for(int j=0;j<n;j++)
       {
           cout<<ar[i][j]<<" ";
       }
       cout<<endl;
   }
	return 0;
}
    
    
         

2D Array Staircase Search in C++

#include<bits/stdc++.h>

using namespace std;

void stairCaseSearch(vector<vector<int>> arr, int n, int el) {
    int i=0, j=n-1;
    while(i<n && j>=0) {
        if(el==arr[i][j]) {
            cout<<"Found at row = "<<i+1<<" and column = "<<j+1;
            return ;
        } else if(el<arr[i][j])
            j--;
        else if(el>arr[i][j])
            i++;
    }
    cout<<"Not found";
    return;
}
int main() {
    int n, el;
    cout<<"Enter no of row: ";
    cin>>n;
    cout<<"Enter no of column: ";
    cin>>el;
	vector<vector<int>> arr(n, vector<int> (n));
    for(int i=0; i<n; i++) {
        for(int j=0; j<n; j++) {
            cin>>arr[i][j];
        }
    }
    stairCaseSearch(arr,n,el);
	return 0;
}

2D Array Read Character/Strings From User in C++

#include<bits/stdc++.h>
#include<iostream>
using namespace std;

int main(){

char ch[1000][1000];
//Read a list of string and we will store them in a 2d character
int n;
cout<<"Enter no of line: ";
cin>>n;
cin.get();
for(int i=0; i<n; i++){
  cout<<"Enter character or Words: ";
  cin.getline(ch[i], 1000);
}

for(int j=0; j<n; j++){
  cout<<ch[j]<<endl;
}
return 0 ;
}