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

bool isPossible(int **input, int i, int j, int num) {
  for(int r = 0; r < 9; r++) {
    if(input[r][j] == num || input[i][r] == num) return false;
  }
  
  int row = (i / 3) * 3, col = (j / 3) * 3;
  for(int r = row; r < row + 3; r++) {
    for(int c = col; c < col + 3; c++) {
      if(input[r][c] == num) return false;    
    }
  }
  
  return true;
}

bool sodukuSolver(int **input, int i, int j) {
  if(i == 9) {
    return true;
  }
  
  if(j == 9) {
    return sodukuSolver(input, i + 1, 0);
  }
  
  if(input[i][j] == 0) {
    for(int num = 1; num <= 9; num++) {
      if(isPossible(input, i, j, num)) {
        input[i][j] = num;
        if(sodukuSolver(input, i, j + 1)) {
           return true;
        }
      }
    }
    input[i][j] = 0;
    return false;
  } else {
    return sodukuSolver(input, i, j + 1);
  }
}

int main() 
{
    int **input = new int*[9];
    for(int i = 0; i < 9; i++) {
      input[i] = new int[9];
      char s[10];
      cin>>s;
      for(int j = 0; s[j] != '\0'; j++) {
        input[i][j] = s[j] - '0';
      }
    }
    
    bool canSolve = sodukuSolver(input, 0, 0);
    
    if(canSolve) {
      cout << "Soduku Can Be Solved In Following Way :" << endl;
      for(int i = 0; i < 9; i++) {
        for(int j = 0; j < 9; j++) {
          cout<<input[i][j];
        }
        cout<<endl;
      }
    } else {
      cout << endl << "Soduku Cannot Be Solved" << endl;
    }
    return 0;
}
by

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}