54. Spiral Matrix
Problem
Given an m x n matrix, return all elements of the matrix in spiral order.
Example
Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
Output: [1,2,3,6,9,8,7,4,5]
[1] Code (21. 02. 16)
class Solution {
int[] dx = { 0, 1, 0, -1 };
int[] dy = { 1, 0, -1, 0 };
public List<Integer> spiralOrder(int[][] matrix) {
List<Integer> answer = new LinkedList<>();
boolean[][] isVisit = new boolean[matrix.length][matrix[0].length];
return solve(answer, matrix, isVisit, 0, 0, 0);
}
private List<Integer> solve(List<Integer> answer, int[][] matrix, boolean[][] isVisit,
int dir, int x, int y) {
isVisit[x][y] = true;
answer.add(matrix[x][y]);
int nx = x + dx[dir];
int ny = y + dy[dir];
int nextDir = getNextDirection(dir + 1);
int nx2 = x + dx[nextDir];
int ny2 = y + dy[nextDir];
if (isInRange(matrix, nx, ny)
&& isVisit[nx][ny] == false) {
solve(answer, matrix, isVisit, dir, nx, ny);
} else if (isInRange(matrix, nx2, ny2)
&& isVisit[nx2][ny2] == false) {
solve(answer, matrix, isVisit, nextDir, nx2, ny2);
}
return answer;
}
private int getNextDirection(int dir) {
return dir % 4;
}
private boolean isInRange(int[][] matrix, int x, int y) {
return x >= 0 && x < matrix.length && y >= 0 && y < matrix[0].length;
}
}
Check Point
-
달팽이 모양으로 순회하면서 인자 값 출력
-
input 값에 대해서는 고려하지 않아도 됨
-
코너 케이스는 따로 없어 보임
Algorithm Description
- 단순 구현문제