Question Definition
Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.
For example, Given the following matrix:
[
[ 1, 2, 3 ],
[ 4, 5, 6 ],
[ 7, 8, 9 ]
]
You should return [1,2,3,6,9,8,7,4,5].
Java Solution
public List<Integer> spiralOrder(int[][] matrix) {
List<Integer> result = new LinkedList<>();
if(matrix.length == 0)
return result;
int level = 0;
int m = matrix.length;
int n = matrix[0].length;
int i = 0;
int j = 0;
int direction = 0;
while(result.size() < m * n){
result.add(matrix[i][j]);
if(direction == 0){
if(j + level == n - 1){
i++;
direction = 1;
}else
j++;
}else if(direction == 1){
if(i + level == m - 1){
j--;
direction = 2;
}else
i++;
}else if(direction == 2){
if(j - level == 0){
i--;
direction = 3;
}else
j--;
}else if(direction == 3){
if(i - level == 1){
j++;
direction = 0;
level++;
}else
i--;
}
}
return result;
}
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