# Find orientation of a pattern in a matrix in C++

C++Server Side ProgrammingProgramming

In this problem, we are given a matrix consisting of character values that make a pattern, we are also given a pattern to be found. Our task is to find the orientation (horizontal or vertical) of a pattern in a matrix.

Let’s take an example to understand the problem,

## Input

mat[][] = {
{ r, a, m },
{a, m, c},
{w, f, t}
}
Patern : raw

## Output

vertical

## Solution Approach

A simple solution to the problem is by searching the M sized pattern in all the N rows of the matrix. This solution is ok but a more effective solution to the problem is by using the KML pattern matching algorithm for all rows and columns of the matrix.

Program to illustrate the working of our solution,

## Example

Live Demo

#include<bits/stdc++.h>
using namespace std;
#define N 3
void calcLpsValues(char *pat, int M, int *lps) {
int len = 0;
int i = 1;
lps = 0;
while (i < M) {
if (pat[i] == pat[len]) {
len++;
lps[i++] = len;
} else {
if (len != 0)
len = lps[len - 1];
else
lps[i++] = 0;
}
}
}
int searchPattern(char *pat, char *txt) {
int M = strlen(pat);
int *lps = (int *)malloc(sizeof(int)*M);
int j = 0;
calcLpsValues(pat, M, lps);
int i = 0;
while (i < N) {
if (pat[j] == txt[i]) {
j++;
i++;
}
if (j == M)
return 1;
else if (i < N && pat[j] != txt[i]) {
if (j != 0)
j = lps[j - 1];
else
i = i + 1;
}
}
return 0;
}
void findPatternOrientation(char mat[][N], char *pat) {
char *col = (char*) malloc(N);
for (int i = 0; i < N; i++) {
if (searchPattern(pat, mat[i])) {
cout<<"horizontal";
return;
}
for (int j = 0; j < N; j++)
col[j] = *(mat[j] + i);
if (searchPattern(pat, col))
cout<<"vertical";
}
}
int main() {
char mat[N][N] = {{'r', 'a', 'm'},
{'a', 'm', 'c'},
{'w', 'f', 't'}};
char pattern[] = "raw";
cout<<"The orientation of the pattern in matrix is ";
findPatternOrientation(mat, pattern);
return 0;
}

## Output

The orientation of the pattern in matrix is vertical