leetcode: Spiral Matrix

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]

.

注意各个边界条件，i，j的++，--错了好多次，还有最后的条件判断也要注意

class Solution {
public:
vector<int> spiralOrder(vector<vector<int> > &matrix) {
vector< int> res;
if( matrix.size() == 0)
return res;
int m = matrix[0].size();
int n = matrix.size();
int i = 0, j = 0;
while( m >= 2 && n >= 2){
for( int k = 0; k < m; ++k, ++j)
res.push_back( matrix[i][j]);
--j; ++i;
for( int k = 0; k < n - 1; ++k, ++i)
res.push_back( matrix[i][j]);
--i; --j;
for( int k = 0; k < m - 1; ++k, --j)
res.push_back( matrix[i][j]);
++j; --i;
for( int k = 0; k < n - 2; ++k, --i)
res.push_back( matrix[i][j]);
++i; ++j;
m -= 2;
n -= 2;
}
if( n >= 2 && m == 1){//m == 1这个条件必须加
for( int k = 0; k < n; ++k, ++i)
res.push_back( matrix[i][j]);
}
else if( m >= 2 && n == 1){
for( int k = 0; k < m; ++k, ++j)
res.push_back( matrix[i][j]);
}
else if( m == 1 && n == 1)
res.push_back( matrix[i][j]);
else
;
return res;
}
};