Square-Free Division (easy version) (Codeforces 1497E1)
Tags: Math, two pointers

This is the easy version of the problem. The only difference is that in this version $$$k = 0$$$.There is an array $$$a_1, a_2, \ldots, a_n$$$ of $$$n$$$ positive integers. You should divide it into a minimal number of continuous segments, such that in each segment there are no two numbers (on different positions), whose product is a perfect square.Moreover, it is allowed to do at most $$$k$$$ such operations before the division: choose a number in the array and change its value to any positive integer. But in this version $$$k = 0$$$, so it is not important.What is the minimum number of continuous segments you should use if you will make changes optimally?

Input: The first line contains a single integer $$$t$$$ $$$(1 \le t \le 1000)$$$  — the number of test cases.The first line of each test case contains two integers $$$n$$$, $$$k$$$ ($$$1 \le n \le 2 \cdot 10^5$$$, $$$k = 0$$$).The second line of each test case contains $$$n$$$ integers $$$a_1, a_2, \ldots, a_n$$$ ($$$1 \le a_i \le 10^7$$$).It's guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2 \cdot 10^5$$$.

Output: For each test case print a single integer  — the answer to the problem.

Note: In the first test case the division may be as follows:  $$$[18, 6]$$$  $$$[2, 4]$$$  $$$[1]$$$ 

Sample Inputs:
3
5 0
18 6 2 4 1
5 0
6 8 1 24 8
1 0
1

Sample Outputs:
3
2
1

Solution (Python):
import time
import os, io
input = io.BytesIO(os.read(0, os.fstat(0).st_size)).readline

def nr():
    return int(input())

def nrs():
    return [int(i) for i in input().split()]
N = 3162
p = [1] * N
for i in range(2, N):
    if p[i]:
        for j in range(2 * i, N, i):
            p[j] = 0
p2 = [c * c for c in range(2, N) if p[c]]

def f(a):
    ans = 1
    kl = set()
    hash = {}
    for r0 in a:
        if r0 not in hash:
            r = r0
            for q in p2:
                if r < q:
                    break
                while r % q == 0:
                    r = r // q
            hash[r0] = r
        else:
            r = hash[r0]
        if r in kl:
            ans += 1
            kl = set()
        kl.add(r)
    print(ans)
for _ in range(nr()):
    (_, _) = nrs()
    f(nrs())

Solution (Python):
from calendar import c
from cmath import inf
from math import ceil, gcd, sqrt, log2, factorial
import os
from re import I, M
import sys
from io import BytesIO, IOBase
from collections import Counter, defaultdict, deque
from heapq import heappush, heappop, heapify
from collections import defaultdict
mod = 10 ** 9 + 7
mod1 = 998244353
BUFSIZE = 8192

class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = 'x' in file.mode or 'r' not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            (self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr))
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b'\n') + (not b)
            ptr = self.buffer.tell()
            (self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr))
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            (self.buffer.truncate(0), self.buffer.seek(0))

class IOWrapper(IOBase):

    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode('ascii'))
        self.read = lambda : self.buffer.read().decode('ascii')
        self.readline = lambda : self.buffer.readline().decode('ascii')
(sys.stdin, sys.stdout) = (IOWrapper(sys.stdin), IOWrapper(sys.stdout))
input = lambda : sys.stdin.readline().rstrip('\r\n')

def lcm(a, b):
    return a * b // gcd(a, b)
''

class SortedList:

    def __init__(self, iterable=[], _load=200):
        """"""
        values = sorted(iterable)
        self._len = _len = len(values)
        self._load = _load
        self._lists = _lists = [values[i:i + _load] for i in range(0, _len, _load)]
        self._list_lens = [len(_list) for _list in _lists]
        self._mins = [_list[0] for _list in _lists]
        self._fen_tree = []
        self._rebuild = True

    def _fen_build(self):
        """"""
        self._fen_tree[:] = self._list_lens
        _fen_tree = self._fen_tree
        for i in range(len(_fen_tree)):
            if i | i + 1 < len(_fen_tree):
                _fen_tree[i | i + 1] += _fen_tree[i]
        self._rebuild = False

    def _fen_update(self, index, value):
        """"""
        if not self._rebuild:
            _fen_tree = self._fen_tree
            while index < len(_fen_tree):
                _fen_tree[index] += value
                index |= index + 1

    def _fen_query(self, end):
        """"""
        if self._rebuild:
            self._fen_build()
        _fen_tree = self._fen_tree
        x = 0
        while end:
            x += _fen_tree[end - 1]
            end &= end - 1
        return x

    def _fen_findkth(self, k):
        """"""
        _list_lens = self._list_lens
        if k < _list_lens[0]:
            return (0, k)
        if k >= self._len - _list_lens[-1]:
            return (len(_list_lens) - 1, k + _list_lens[-1] - self._len)
        if self._rebuild:
            self._fen_build()
        _fen_tree = self._fen_tree
        idx = -1
        for d in reversed(range(len(_fen_tree).bit_length())):
            right_idx = idx + (1 << d)
            if right_idx < len(_fen_tree) and k >= _fen_tree[right_idx]:
                idx = right_idx
                k -= _fen_tree[idx]
        return (idx + 1, k)

    def _delete(self, pos, idx):
        """"""
        _lists = self._lists
        _mins = self._mins
        _list_lens = self._list_lens
        self._len -= 1
        self._fen_update(pos, -1)
        del _lists[pos][idx]
        _list_lens[pos] -= 1
        if _list_lens[pos]:
            _mins[pos] = _lists[pos][0]
        else:
            del _lists[pos]
            del _list_lens[pos]
            del _mins[pos]
            self._rebuild = True

    def _loc_left(self, value):
        """"""
        if not self._len:
            return (0, 0)
        _lists = self._lists
        _mins = self._mins
        (lo, pos) = (-1, len(_lists) - 1)
        while lo + 1 < pos:
            mi = lo + pos >> 1
            if value <= _mins[mi]:
                pos = mi
            else:
                lo = mi
        if pos and value <= _lists[pos - 1][-1]:
            pos -= 1
        _list = _lists[pos]
        (lo, idx) = (-1, len(_list))
        while lo + 1 < idx:
            mi = lo + idx >> 1
            if value <= _list[mi]:
                idx = mi
            else:
                lo = mi
        return (pos, idx)

    def _loc_right(self, value):
        """"""
        if not self._len:
            return (0, 0)
        _lists = self._lists
        _mins = self._mins
        (pos, hi) = (0, len(_lists))
        while pos + 1 < hi:
            mi = pos + hi >> 1
            if value < _mins[mi]:
                hi = mi
            else:
                pos = mi
        _list = _lists[pos]
        (lo, idx) = (-1, len(_list))
        while lo + 1 < idx:
            mi = lo + idx >> 1
            if value < _list[mi]:
                idx = mi
            else:
                lo = mi
        return (pos, idx)

    def add(self, value):
        """"""
        _load = self._load
        _lists = self._lists
        _mins = self._mins
        _list_lens = self._list_lens
        self._len += 1
        if _lists:
            (pos, idx) = self._loc_right(value)
            self._fen_update(pos, 1)
            _list = _lists[pos]
            _list.insert(idx, value)
            _list_lens[pos] += 1
            _mins[pos] = _list[0]
            if _load + _load < len(_list):
                _lists.insert(pos + 1, _list[_load:])
                _list_lens.insert(pos + 1, len(_list) - _load)
                _mins.insert(pos + 1, _list[_load])
                _list_lens[pos] = _load
                del _list[_load:]
                self._rebuild = True
        else:
            _lists.append([value])
            _mins.append(value)
            _list_lens.append(1)
            self._rebuild = True

    def discard(self, value):
        """"""
        _lists = self._lists
        if _lists:
            (pos, idx) = self._loc_right(value)
            if idx and _lists[pos][idx - 1] == value:
                self._delete(pos, idx - 1)

    def remove(self, value):
        """"""
        _len = self._len
        self.discard(value)
        if _len == self._len:
            raise ValueError('{0!r} not in list'.format(value))

    def pop(self, index=-1):
        """"""
        (pos, idx) = self._fen_findkth(self._len + index if index < 0 else index)
        value = self._lists[pos][idx]
        self._delete(pos, idx)
        return value

    def bisect_left(self, value):
        """"""
        (pos, idx) = self._loc_left(value)
        return self._fen_query(pos) + idx

    def bisect_right(self, value):
        """"""
        (pos, idx) = self._loc_right(value)
        return self._fen_query(pos) + idx

    def count(self, value):
        """"""
        return self.bisect_right(value) - self.bisect_left(value)

    def __len__(self):
        """"""
        return self._len

    def __getitem__(self, index):
        """"""
        (pos, idx) = self._fen_findkth(self._len + index if index < 0 else index)
        return self._lists[pos][idx]

    def __delitem__(self, index):
        """"""
        (pos, idx) = self._fen_findkth(self._len + index if index < 0 else index)
        self._delete(pos, idx)

    def __contains__(self, value):
        """"""
        _lists = self._lists
        if _lists:
            (pos, idx) = self._loc_left(value)
            return idx < len(_lists[pos]) and _lists[pos][idx] == value
        return False

    def __iter__(self):
        """"""
        return (value for _list in self._lists for value in _list)

    def __reversed__(self):
        """"""
        return (value for _list in reversed(self._lists) for value in reversed(_list))

    def __repr__(self):
        """"""
        return 'SortedList({0})'.format(list(self))
''

class SegmentTree:

    def __init__(self, data, default=3 * 10 ** 9, func=lambda a, b: min(a, b)):
        """"""
        self._default = default
        self._func = func
        self._len = len(data)
        self._size = _size = 1 << (self._len - 1).bit_length()
        self.data = [default] * (2 * _size)
        self.data[_size:_size + self._len] = data
        for i in reversed(range(_size)):
            self.data[i] = func(self.data[i + i], self.data[i + i + 1])

    def __delitem__(self, idx):
        self[idx] = self._default

    def __getitem__(self, idx):
        return self.data[idx + self._size]

    def __setitem__(self, idx, value):
        idx += self._size
        self.data[idx] = value
        idx >>= 1
        while idx:
            self.data[idx] = self._func(self.data[2 * idx], self.data[2 * idx + 1])
            idx >>= 1

    def __len__(self):
        return self._len

    def query(self, start, stop):
        if start == stop:
            return self.__getitem__(start)
        stop += 1
        start += self._size
        stop += self._size
        res = self._default
        while start < stop:
            if start & 1:
                res = self._func(res, self.data[start])
                start += 1
            if stop & 1:
                stop -= 1
                res = self._func(res, self.data[stop])
            start >>= 1
            stop >>= 1
        return res

    def __repr__(self):
        return 'SegmentTree({0})'.format(self.data)
n = 10000010
m = [0] * n
for i in range(1, n):
    if m[i] != 0:
        continue
    m[i] = i
    j = 1
    while i * j * j <= n:
        m[i * j * j] = i
        j += 1
for _ in range(int(input())):
    (n, k) = map(int, input().split())
    a = list(map(int, input().split()))
    s = set()
    r = 1
    for i in a:
        if m[i] in s:
            r += 1
            s = set()
        s.add(m[i])
    print(r)

Solution (Python):
import os, io
input = io.BytesIO(os.read(0, os.fstat(0).st_size)).readline
prime = [1] * 10000
prime2 = []
curr = 2
for i in range(2, 10000):
    if prime[i]:
        for j in range(2 * i, 10000, i):
            prime[j] = 0
while curr * curr <= 10 ** 7:
    if prime[curr]:
        prime2.append(curr * curr)
    curr += 1
t = int(input())
for _ in range(t):
    (n, k) = map(int, input().split())
    a = list(map(int, input().split()))
    ans = 1
    kl = set()
    for i in range(n):
        r = a[i]
        for q in prime2:
            if r < q:
                break
            while r % q == 0:
                r = r // q
        if r in kl:
            ans += 1
            kl = set()
            kl.add(r)
        else:
            kl.add(r)
    print(ans)