everyutil/number/spiralNumberMatrix.js

A comprehensive library of lightweight, reusable utility functions for JavaScript and TypeScript, designed to streamline common programming tasks such as string manipulation, array processing, date handling, and more.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.spiralNumberMatrix = void 0;
/**
 * Builds a square matrix of size n x n filled with numbers in spiral order.
 * For example, spiralNumberMatrix(3) returns [[1,2,3],[8,9,4],[7,6,5]].
 * @author @dailker
 * @param {number} n - The size of the matrix (number of rows and columns).
 * @returns {number[][]} The n x n matrix filled in spiral order.
 */
function spiralNumberMatrix(n) {
    const matrix = Array.from({ length: n }, () => Array(n).fill(0));
    let val = 1, top = 0, bottom = n - 1, left = 0, right = n - 1;
    while (top <= bottom && left <= right) {
        for (let i = left; i <= right; i++)
            matrix[top][i] = val++;
        top++;
        for (let i = top; i <= bottom; i++)
            matrix[i][right] = val++;
        right--;
        for (let i = right; i >= left; i--)
            matrix[bottom][i] = val++;
        bottom--;
        for (let i = bottom; i >= top; i--)
            matrix[i][left] = val++;
        left++;
    }
    return matrix;
}
exports.spiralNumberMatrix = spiralNumberMatrix;