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:
std::vector
> generateMatrix(int n) {
std::vector
> matrix(n,std::vector
(n,0)); int start = 0, end = n - 1; int step = 1; while(start < end) { for (int i = start; i < end; i++) { matrix[start][i] = step++; } for (int i = start; i < end; i++) { matrix[i][end] = step++; } for(int i = end; i > start; i--) { matrix[end][i] = step++; } for(int i = end; i > start; i--) { matrix[i][start] = step++; } start++; end--; } if(start == end) { matrix[start][end] = step++; } return matrix; } };