I tried to solve Leetcode Problem 54 - spiral
and got stuck in empty vector input.
the question is about spiral list. input is 2d vector and output should be vector list which written by spiral direction.
Input:
[
[1, 2, 3, 4],
[5, 6, 7, 8],
[9,10,11,12]
]
Output: [1,2,3,4,8,12,11,10,9,5,6,7]
problem is when input is empty list.
Input: []
it produces runtime error.
another testcases passed except empty input like [] .
It seems no runtime error during testing in my mac OSX terminal,
but Leetcode says
'Line 933: Char 34: runtime error: reference binding to null pointer of type 'struct value_type' (stl_vector.h)
'
Here is link
https://leetcode.com/problems/spiral-matrix/
Also I attach codes below ...
class Solution {
public:
vector answer;
int left = 0, right = 0;
vector spiralOrder(vector>& matrix) {
if(matrix[0].size()<1) return {};
vector> flag(matrix.size(),vector(matrix[0].size(),0));
while(1){
flag[left][right] =1;
answer.push_back(matrix[left][right]);
if(right+1=0 && flag[left][right-1]==0){
--right;
continue;
}
else if(left-1>=0 && flag[left-1][right]==0){
--left;
continue;
}
else break;
}
return answer;
}
};