BOJ - 10903 - Wall construction

import sys
import math

_PI = 3.141592653589793

def getDegree(p1, p2):
    return p2[0] - p1[0], p2[1] - p1[1]

def ccw(p1, p2, p3):
    v, u = getDegree(p1, p2), getDegree(p2, p3)
    if v[0] * u[1] > v[1] * u[0]: return True
    else: return False

def convex_hull(position):
    convex = []
    for p3 in position:
        while len(convex) >= 2:
            p1, p2 = convex[-2], convex[-1]
            if ccw(p1, p2, p3):
                break
            convex.pop()
        convex.append(p3)
    return convex

def getPointLength(p1, p2):
    return math.sqrt(math.pow(p2[0] - p1[0], 2) + math.pow(p2[1] - p1[1], 2))

def solution():
    N, M = map(int, sys.stdin.readline().split())

    position = []
    for _ in range(N):
        x, y = map(str, sys.stdin.readline().split())
        position.append((int(x), int(y)))

    position = sorted(position, key=lambda x:(x[0], x[1]))
    ccwtemp = convex_hull(position)

    position.reverse()
    temp = convex_hull(position)

    for i in range(1, len(temp)):
        ccwtemp.append(temp[i])

    ret = 0
    for i in range(len(ccwtemp) - 1):
        ret += getPointLength(ccwtemp[i], ccwtemp[i+1])
    ret += M * 2 * _PI
    print(ret)


solution()

https://www.acmicpc.net/problem/10903