(function(){
    const SEED = BigInt('0xDEADBEEF');
    const ROWS = 100;
    const COLS = 100;
    const COLORS_NUM = 3;

    let LCGRand = function() {
        this.next = SEED;
        this.A = BigInt('6364136223846793005');
        this.C = BigInt('1442695040888963407');
        this.M = BigInt('0xFFFFFFFFFFFFFFFF');
        this.SHIFT = BigInt('32');
        return function() {
            this.next = (((this.next * this.A) & this.M) + this.C) & this.M;
            return this.next >> this.SHIFT;
        };
    }();

    function matrixAt(matrix, i, j) {
        return matrix[i * COLS + j];
    }

    function generateMatrix() {
        let matrix = [];
        for (let i = 0; i < ROWS * COLS; i++) {
            matrix.push({
                color: Number(LCGRand()) % COLORS_NUM,
                visited: false
            });
        }
        return matrix;
    }

    function isValidCoords(i, j) {
        return (i >= 0) && (i < ROWS) && (j >= 0) && (j < COLS);
    }

    function visitNode(matrix, i, j) {
        const MOVES = [
            [ -1, 0 ],
            [ +1, 0 ],
            [ 0, -1 ],
            [ 0, +1 ],
        ];

        let vec = [[i, j]];
        let blockSize = 0;
        let currentNode = matrixAt(matrix, i, j);
        const targetColor = currentNode.color;
        currentNode.visited = true;
        while (vec.length > 0) {
            [i, j] = vec.pop();
            blockSize++;

            for (let move of MOVES) {
                let movedI = i + move[0], movedJ = j + move[1];
                if (isValidCoords(movedI, movedJ)) {
                    let node = matrixAt(matrix, movedI, movedJ);
                    if (node.color === targetColor && !node.visited) {
                        node.visited = true;
                        vec.push([movedI, movedJ]);
                    }
                }
            }
        }
        return blockSize;
    }

    function main() {
        let matrix = generateMatrix();
        let maxBlockSize = 0;

        let startTime = performance.now();
        for (let i = 0; i < ROWS; i++) {
            for (let j = 0; j < COLS; j++) {
                if (!matrixAt(matrix, i, j).visited) {
                    const blockSize = visitNode(matrix, i, j);
                    if (maxBlockSize < blockSize) {
                        maxBlockSize = blockSize;
                    }
                }
            }
        }

        console.log('Max block size: ' + maxBlockSize);
        console.log('Time: ' + (performance.now() - startTime));
    }

    main();
})();