generateMatrix 给定N 返回指定矩阵

public:
vector<vector<int>> generateMatrix(int n) {
vector<vector<int>> result;
unsigned long m = (unsigned long)n;
result.resize(m);
for (int i1 = 0; i1 < m; ++i1) {
result[i1].resize(m);
}

int k = n / 2 ;
if(n%2 == 0)
k-=1;
int count = 0;
int begin = 1;
for (int i = 0; i <= k; ++i) {
for (int j = i; j < n; ++j) {
result[i][j] = begin++;
}
for (int l = i + 1; l < n; ++l) {
result[l][n-1] = begin ++;
}
for (int s = n-2; s >=i ; s--) {
result[n-1][s] = begin ++;
}
for (int p = n-2; p > i ; p--) {
result[p][i] = begin ++;
}

n -= 1;

}
return result;
}
};