1407D - Discrete Centrifugal Jumps - CodeForces Solution

import random
import sys
import os
import math
from bisect import bisect_left, bisect_right
from collections import Counter, defaultdict, deque
from functools import lru_cache, reduce
from itertools import accumulate, combinations, permutations
from heapq import nsmallest, nlargest, heapify, heappop, heappush
from io import BytesIO, IOBase
from copy import deepcopy

BUFSIZE = 4096
MAX = (1 << 63) - 1
MIN = -MAX


class Segment:
    def __init__(self, n):
        self.sgm_tree = [0 for i in range(2 * n)]
        self.d = {}

    def queries(self, l, r):
        count = 0
        while l <= r:
            if l % 2 == 1:
                count += self.sgm_tree[l]
                l += 1
            if r % 2 == 0:
                count += self.sgm_tree[r]
                r -= 1
            l = l >> 1
            r = r >> 1
        return count

    def update(self, indx, num):
        if num == 2:
            self.d[indx] -= 1
            if self.d[indx] == 0:
                self.sgm_tree[indx] = 0
        else:
            if indx not in self.d:
                self.d[indx] = 0
            self.d[indx] += 1
            if self.d[indx] == 1:
                self.sgm_tree[indx] = 1
        indx = indx >> 1
        while indx >= 1:
            self.sgm_tree[indx] = self.sgm_tree[2 * indx] + self.sgm_tree[2 * indx + 1]
            indx = indx >> 1


class FenwickTree:
    def __init__(self, n):
        self.n = n
        self.bit = [0] * n

    def sum(self, r):
        res = 0
        while r >= 0:
            res += self.bit[r]
            r = (r & (r + 1)) - 1
        return res

    def rsum(self, l, r):
        return self.sum(r) - self.sum(l - 1)

    def add(self, idx, delta):
        while idx < self.n:
            self.bit[idx] += delta
            idx = idx | (idx + 1)


def gcd(a, b):
    if a < 0: a = -a
    if b < 0: b = -b
    if a < b:
        a, b = b, a
    if a % b == 0:
        return b
    return gcd(b, a % b)


def toposort(graph):
    res, found = [], [0] * len(graph)
    stack = list(range(len(graph)))
    while stack:
        node = stack.pop()
        if node < 0:
            res.append(~node)
        elif not found[node]:
            found[node] = 1
            stack.append(~node)
            stack += graph[node]

        for node in res:
        if any(found[nei] for nei in graph[node]):
            return None
        found[node] = 0

    return res[::-1]


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 I():
    return input()


def II():
    return int(input())


def MI():
    return map(int, input().split())


def LI():
    return list(input().split())


def LII():
    return list(map(int, input().split()))


def TMI(arr):
    return list(map(str, arr))


def GMI():
    return map(lambda x: int(x) - 1, input().split())


def LGMI():
    return list(GMI())


n = II()
h = LII()
dp = [0] * n
stka,stkb = [0],[0]
for i in range(1,n):
    dp[i] = dp[i - 1] + 1
    while stka and h[stka[-1]] >= h[i]:
        tmp = stka.pop()
        if h[tmp] > h[i] and stka:
            dp[i] = min(dp[i],dp[stka[-1]] + 1)
    while stkb and h[stkb[-1]] <= h[i]:
        tmp = stkb.pop()
        if h[tmp] < h[i] and stkb:
            dp[i] = min(dp[i],dp[stkb[-1]] + 1)
    stka.append(i)
    stkb.append(i)
print(dp[n - 1])