package com.github.jerring.leetcode;

import java.util.ArrayList;

import java.util.List;

public class LeetCode_00054 {

public List<Integer> spiralOrder(int[][] matrix) {

if (matrix.length == 0 || matrix[0].length == 0) {

return new ArrayList<>();

}

int top = 0, bottom = matrix.length - 1;

int left = 0, right = matrix[0].length - 1;

List<Integer> res = new ArrayList<>();

while (top <= bottom && left <= right) {

processEdge(matrix, top++, bottom--, left++, right--, res);

}

return res;

}

private void processEdge(int[][] matrix, int top, int bottom, int left, int right, List<Integer> res) {

if (top == bottom) {

for (int i = left; i <= right; ++i) {

res.add(matrix[top][i]);

}

return;

}

if (left == right) {

for (int i = top; i <= bottom; ++i) {

res.add(matrix[i][right]);

}

return;

}

int i = top, j = left;

while (j != right) {

res.add(matrix[i][j++]);

}

while (i != bottom) {

res.add(matrix[i++][j]);

}

while (j != left) {

res.add(matrix[i][j--]);

}

while (i != top) {

res.add(matrix[i--][j]);

}

}

}