Given a positive integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.
Example:
Input: 3 Output: [ [ 1, 2, 3 ], [ 8, 9, 4 ], [ 7, 6, 5 ] ]
public class Solution {
public int[][] GenerateMatrix(int n) {
var result = new int[n][];
for(int i=0;i<n;i++){
result[i]=new int[n];
}
int index = 1;
int sx = 0;
int sy = 0;
int ex = n;
int ey = n;
while(sx < ex && sy < ey){
for(int i=sy;i<ey;i++){
result[sx][i]=index;
index++;
}
sx++;
for(int i=sx;i<ex;i++){
result[i][ey-1]=index;
index++;
}
ey--;
if(sx<ex){
for(int i=ey-1;i>=sy;i--){
result[ex-1][i]=index;
index++;
}
ex--;
}
if(sy<ey){
for(int i=ex-1;i>=sx;i--){
result[i][sy]=index;
index++;
}
sy++;
}
}
return result;
}
}Time Complexity: O(n^2)
Space Complexity: O(n^2)
