Spiral Matrix I I Algorithm
The Spiral Matrix II algorithm is a unique approach to generating a matrix in a spiral pattern. It is often employed to create a square matrix, where elements are arranged in a spiral order, starting from the top left corner and moving inwards in a clockwise direction. This algorithm is useful in various applications, including image processing, data manipulation, and problem-solving tasks that require the arrangement of elements in a specific pattern.
To implement the Spiral Matrix II algorithm, a two-dimensional array or matrix is initialized with the dimensions provided, typically in the form of an integer, n, where the matrix size is n x n. The algorithm then iterates through the matrix, filling each element with an incrementing value, starting from 1, while traversing the matrix in a spiral pattern. The traversal is performed using four loops, corresponding to each direction of the spiral: right, down, left, and up. These loops ensure that the matrix is filled in the correct order, with each element being assigned a unique value. The process continues until all elements in the matrix are assigned their respective values, ultimately forming the desired spiral matrix.
class Solution {
public:
vector<vector<int> > generateMatrix(int n) {
vector<vector<int>> matrix(n, vector<int>(n, 0));
int dir[4][2] = {0, 1, 1, 0, 0, -1, -1, 0};
int x = 0;
int y = -1;
int k = 0;
int count = 0;
int horizon = true;
int row = n;
int col = n + 1;
while (count < n * n) {
int dx = dir[k%4][0];
int dy = dir[k%4][1];
k++;
if (horizon) {
horizon = false;
col--;
for (int i = 0; i < col; i++) {
x += dx;
y += dy;
count++;
matrix[x][y] = count;
}
} else {
horizon = true;
row--;
for (int i = 0; i < row; i++) {
x += dx;
y += dy;
count++;
matrix[x][y] = count;
}
}
}
return matrix;
}
};
