Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.
For example,
Given n = 3
,
[ [ 1, 2, 3 ], [ 8, 9, 4 ], [ 7, 6, 5 ] ]
class Solution {
public:
vector<vector<int> > generateMatrix(int n) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
vector<vector<int> > result(n, vector<int>(n));
if (n == 0) return result;
int num = 0;
int layer = n/2;
for (int i = 0; i < layer; ++i)
{
int j;
for (j = i; j < n-1-i; ++j)
result[i][j] = ++num;
for (j = i; j < n-1-i; ++j)
result[j][n-1-i] = ++num;
for (j = n-1-i; j > i; --j)
result[n-1-i][j] = ++num;
for (j = n-1-i; j > i; --j)
result[j][i] = ++num;
}
if (n%2 == 1)
result[n/2][n/2] = ++num;
return result;
}
};