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| class Solution {
public:
struct Runner
{
int leftBorder;
int rightBorder;
int topBorder;
int downBorder;
int dir;
int counter;
int x;
int y;
Runner(int n)
{
leftBorder = 0;
rightBorder = n;
topBorder = 0;
downBorder = n;
dir = 1;
counter = 0;
x = 0;
y = 0;
}
};
void goRight(vector<vector<int>>& m, int n, Runner& r)
{
if (r.x < r.rightBorder)
{
++r.counter;
m[r.y][r.x] = r.counter;
++r.x;
}
else
{
r.dir = 2;
++r.topBorder;
++r.y;
--r.x;
}
}
void goLeft(vector<vector<int>>& m, int n, Runner& r)
{
if (r.x >= r.leftBorder)
{
++r.counter;
m[r.y][r.x] = r.counter;
--r.x;
}
else
{
r.dir = 3;
--r.downBorder;
--r.y;
++r.x;
}
}
void goDown(vector<vector<int>>& m, int n, Runner& r)
{
if (r.y < r.downBorder)
{
++r.counter;
m[r.y][r.x] = r.counter;
++r.y;
}
else
{
r.dir = 0;
--r.rightBorder;
--r.x;
--r.y;
}
}
void goUp(vector<vector<int>>& m, int n, Runner& r)
{
if (r.y >= r.topBorder)
{
++r.counter;
m[r.y][r.x] = r.counter;
--r.y;
}
else
{
r.dir = 1;
++r.leftBorder;
++r.x;
++r.y;
}
}
vector<vector<int>> generateMatrix(int n) {
vector<vector<int>> result(n,vector<int>(n,0));
int num = n * n;
Runner r(n);
while(r.counter < num)
{
if (r.dir == 0)
{
goLeft(result,n,r);
}
else if (r.dir == 1)
{
goRight(result,n,r);
}
else if (r.dir == 2)
{
goDown(result,n,r);
}
else
{
goUp(result,n,r);
}
}
return result;
}
};
|