class Matrix{
    constructor(width, height, element = (x, y) => undefined) {

        this.width = width;
        this.height = height;
        this.content = [];

        for(let y = 0; y < height; y++){
            for(let x = 0; x < width; x++){
                this.content[y * width + x ] = element(x,y);
            }
        }
    }

    get(x,y) {
        return this.content[y * this.width + x];
    }
    set(x, y, value){
        this.content[y * this.width + x] = value;
    }
}

class SymmetricMatrix extends Matrix {
    constructor(size, element = (x,y) => undefined) {
        super(size, size, (x,y) => {
            if (x < y) return element(y,x);
            else return element(x,y);
        });
    }

        set(x, y, value) {
            super.set(x, y, value);
            if (x != y) {
            super.set(y, x, value);
        }
    }
}