freecodecamp--freecodecamp/curriculum/challenges/english/blocks/daily-coding-challenges-python/6a19b1062d1b153d8ac76d70.md

id, title, challengeType, dashedName

id	title	challengeType	dashedName
6a19b1062d1b153d8ac76d70	Challenge 322: Connect 3	29	challenge-322

--description--

Given a matrix of strings representing pieces on a game grid, determine if any player has three in a row.

• Each cell contains "R", "Y", or "" (empty string).
• Three in a row means three consecutive non-empty cells of the same type horizontally, vertically, or diagonally.

Return:

• A flat array with the winner and the coordinates of their three winning cells in the format: ["R", [0,2], [1,3], [2,4]]. Coordinates are returned top-to-bottom, then left-to-right.
• An empty array if there is no winner.

--hints--

connect_three([["", "", "", ""], ["", "", "", ""], ["", "Y", "", ""], ["Y", "R", "R", "R"]]) should return ["R", [3, 1], [3, 2], [3, 3]].

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(connect_three([["", "", "", ""], ["", "", "", ""], ["", "Y", "", ""], ["Y", "R", "R", "R"]]), ["R", [3, 1], [3, 2], [3, 3]])`)
}})

connect_three([["", "", "", ""], ["", "Y", "Y", ""], ["", "Y", "R", "R"], ["", "Y", "R", "R"]]) should return ["Y", [1, 1], [2, 1], [3, 1]].

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(connect_three([["", "", "", ""], ["", "Y", "Y", ""], ["", "Y", "R", "R"], ["", "Y", "R", "R"]]), ["Y", [1, 1], [2, 1], [3, 1]])`)
}})

connect_three([["", "", "Y", "R"], ["", "Y", "R", "Y"], ["", "R", "Y", "R"], ["", "R", "Y", "R"]]) should return ["R", [0, 3], [1, 2], [2, 1]].

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(connect_three([["", "", "Y", "R"], ["", "Y", "R", "Y"], ["", "R", "Y", "R"], ["", "R", "Y", "R"]]), ["R", [0, 3], [1, 2], [2, 1]])`)
}})

connect_three([["", "Y", "", ""], ["", "Y", "Y", ""], ["", "R", "R", "Y"], ["R", "R", "Y", "R"]]) should return ["Y", [0, 1], [1, 2], [2, 3]].

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(connect_three([["", "Y", "", ""], ["", "Y", "Y", ""], ["", "R", "R", "Y"], ["R", "R", "Y", "R"]]), ["Y", [0, 1], [1, 2], [2, 3]])`)
}})

connect_three([["Y", "R", "R", "Y"], ["R", "Y", "Y", "R"], ["Y", "R", "R", "Y"], ["R", "Y", "Y", "R"]]) should return [].

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(connect_three([["Y", "R", "R", "Y"], ["R", "Y", "Y", "R"], ["Y", "R", "R", "Y"], ["R", "Y", "Y", "R"]]), [])`)
}})

--seed--

--seed-contents--

def connect_three(matrix):

    return matrix

--solutions--

def connect_three(matrix):
    rows = len(matrix)
    cols = len(matrix[0])

    directions = [[0, 1], [1, 0], [1, 1], [1, -1]]

    for r in range(rows):
        for c in range(cols):
            piece = matrix[r][c]
            if not piece:
                continue

            for dr, dc in directions:
                cells = [[r, c]]

                for i in range(1, 3):
                    nr = r + dr * i
                    nc = c + dc * i
                    if nr < 0 or nr >= rows or nc < 0 or nc >= cols:
                        break
                    if matrix[nr][nc] != piece:
                        break
                    cells.append([nr, nc])

                if len(cells) == 3:
                    cells.sort(key=lambda x: (x[0], x[1]))
                    return [piece] + cells

    return []