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Construct a linked list from 2D matrix in C++
Suppose we have one matrix, we have to convert it to 2d linked list using recursive approach.
The list will have the right and down pointer.
So, if the input is like
| 10 | 20 | 30 |
| 40 | 50 | 60 |
| 70 | 80 | 90 |
then the output will be
To solve this, we will follow these steps −
Define a function make_2d_list(), this will take matrix mat, i, j, m, n,
if i and j are not in the matrix boundary, then −
return null
temp := create a new node with value mat[i, j]
right of temp := make_2d_list(mat, i, j + 1, m, n)
down of temp := make_2d_list(mat, i + 1, j, m, n)
return temp
Example
Let us see the following implementation to get better understanding −
#include <bits/stdc++.h>
using namespace std;
class TreeNode {
public:
int data;
TreeNode *right, *down;
TreeNode(int d){
data = d;
right = down = NULL;
}
};
void show_2d_list(TreeNode* head) {
TreeNode *right_ptr, *down_ptr = head;
while (down_ptr) {
right_ptr = down_ptr;
while (right_ptr) {
cout << right_ptr->data << " ";
right_ptr = right_ptr->right;
}
cout << endl;
down_ptr = down_ptr->down;
}
}
TreeNode* make_2d_list(int mat[][3], int i, int j, int m, int n) {
if (i > n - 1 || j > m - 1)
return NULL;
TreeNode* temp = new TreeNode(mat[i][j]);
temp->right = make_2d_list(mat, i, j + 1, m, n);
temp->down = make_2d_list(mat, i + 1, j, m, n);
return temp;
}
int main() {
int m = 3, n = 3;
int mat[][3] = {
{ 10, 20, 30 },
{ 40, 50, 60 },
{ 70, 80, 90 } };
TreeNode* head = make_2d_list(mat, 0, 0, m, n);
show_2d_list(head);
}Input
{ { 10, 20, 30 },
{ 40, 50, 60 },
{ 70, 80, 90 } }Output
10 20 30 40 50 60 70 80 90
Updated on: 27-Aug-2020
752 Views
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