fork download
copy 
  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. bool isBorder(int r, int c, int rows, int cols) {
  5.     return r == 0 || r == rows - 1 || c == 0 || c == cols - 1;
  6. }
  7.  
  8. int getExpectedValue(int idx) {
  9.     if (idx == 0) return 1;
  10.     return (idx % 2 == 1) ? 2 : 0;
  11. }
  12.  
  13. int solution(vector<vector<int>>& matrix) {
  14.     int rows = matrix.size();
  15.     int cols = matrix[0].size();
  16.     int maxLen = 0;
  17.  
  18.     // All 4 diagonal directions
  19.     vector<pair<int, int>> directions = {
  20.         {1, 1},   // ↘
  21.         {1, -1},  // ↙
  22.         {-1, 1},  // ↗
  23.         {-1, -1}  // ↖
  24.     };
  25.  
  26.     for (int r = 0; r < rows; ++r) {
  27.         for (int c = 0; c < cols; ++c) {
  28.             // Only start if the cell is 1 (pattern starts with 1)
  29.             if (matrix[r][c] != 1) continue;
  30.  
  31.             for (auto& dir : directions) {
  32.                 int len = 0;
  33.                 int i = r, j = c;
  34.                 while (i >= 0 && i < rows && j >= 0 && j < cols) {
  35.                     if (matrix[i][j] != getExpectedValue(len)) break;
  36.                     len++;
  37.                     i += dir.first;
  38.                     j += dir.second;
  39.                 }
  40.  
  41.                 // Check if the last valid position was on the border
  42.                 int last_i = r + dir.first * (len - 1);
  43.                 int last_j = c + dir.second * (len - 1);
  44.                 if (len > 0 && isBorder(last_i, last_j, rows, cols)) {
  45.                     maxLen = max(maxLen, len);
  46.                 }
  47.             }
  48.         }
  49.     }
  50.  
  51.     return maxLen;
  52. }
  53.  
  54. int main() {
  55.     vector<vector<int>> matrix = {
  56.         {0, 0, 1, 2},
  57.         {0, 2, 2, 2},
  58.         {2, 1, 0, 1}
  59.     };
  60.  
  61.     cout << solution(matrix) << endl; // Output: 3
  62.     return 0;
  63. }
  64.  
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
3
https://ideone.com/rrwZyq
language:
C++ (gcc 8.3)
created:
5 days ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!