Matrix problems often look intimidating. Too many rows, columns, indices… But most interview questions are built on just a few core patterns. Master these patterns once, and matrix questions become much easier. 1. Spiral Traversal Problem Print matrix elements in spiral order. public static List spiralOrder(int[][] matrix) { List<Integer> result = new ArrayList<>(); int top = 0, bottom = matrix.length - 1; int left = 0, right = matrix[0].length - 1; while (top <= bottom && left <= right) { for (int i = left; i <= right; i++) result.add(matrix[top][i]); top++; for (int i = top; i <= bottom; i++) result.add(matrix[i][right]); right--; if (top <= bottom) { for (int i = right; i >= left; i--) result.add(matrix[bottom][i]); bottom--; } if (left <= right) { for (int i = bottom; i >= top; i--) result.add(matrix[i][left]); left++; } } return result; Enter fullscreen mode Exit fullscreen mode } Core Idea Maintain 4 boundaries: top bottom left right Move inward layer by…