sol1.py

"""
Problem 206 : https://projecteuler.net/problem=206

Find the unique positive integer whose square has the form 1_2_3_4_5_6_7_8_9_0,
where each “_” is a single digit.

Solution: Finding a square number can found by adding consecutive odd numbers
starting from 1. The minimum number possible for perfect square is 1020304050607080900
in this situation, so started checking digits are in correct places after
total is above it.
"""

import math


def solution() -> int:
    """
    >>> solution()
    1389019170
    """

    # adding odds
    total = 1
    add = 1

    while True:

        # adding odds
        add += 2
        total += add

        # starts count here since the bottom limit
        if total > 1020304050607080900:

            # nested if statements to check digits
            num = str(total)
            if int(num[-1]) == 0:
                if int(num[-3]) == 9:
                    if int(num[-5]) == 8:
                        if int(num[-7]) == 7:
                            if int(num[-9]) == 6:
                                if int(num[-11]) == 5:
                                    if int(num[-13]) == 4:
                                        if int(num[-15]) == 3:
                                            if int(num[-17]) == 2:
                                                if int(num[-19]) == 1:
                                                    break

    return int(math.sqrt(total))


if __name__ == "__main__":
    print(f"{solution() = }")