提出 #71671887

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ソースコード 拡げる

import sys
import string
import math
import bisect
import os
import heapq
import operator
from io import BytesIO, IOBase
from heapq import heappop,heappush
from functools import lru_cache,cache
from collections import deque,defaultdict,Counter,OrderedDict
from itertools import permutations,combinations
from array import array

INF = float('inf')
BUFSIZE = 8192

class FastIO(IOBase):
    newlines = 0
 
    def __init__(self, file):
        self._file = 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 = sys.stdin.buffer.readline

ask = lambda *x:print('?',*x,flush=True)
reply = lambda *x:print('!',*x,flush=True)

RI = lambda: int(sys.stdin.readline())
RF = lambda: float(sys.stdin.readline())
RS = lambda: sys.stdin.readline().strip()
RFF = lambda: map(float, sys.stdin.readline().split())
RII = lambda: map(int, sys.stdin.readline().split())
RSS = lambda: map(str, sys.stdin.readline().strip().split())
RIL = lambda: list(RII())
RFL = lambda: list(RFF())
RSL = lambda: list(RSS())

from types import GeneratorType
def bootstrap(f, stack=[]):
    def wrappedfunc(*args, **kwargs):
        if stack:
            return f(*args, **kwargs)
        else:
            to = f(*args, **kwargs)
            while True:
                if type(to) is GeneratorType:
                    stack.append(to)
                    to = next(to)
                else:
                    stack.pop()
                    if not stack:
                        break 
                    to = stack[-1].send(to)
            return to

    return wrappedfunc

    
def main():
    n = RI()
    a = RIL()
    a = [x-1 for x in a]
    
    ans = 0
    vis = [False]*n
    
    p = [0]*n
    for i,x in enumerate(a):
        p[x] = i
        
    for i in range(n):
        if vis[i]==False:
            val = 0
            now = i
            while vis[now]==False:
                vis[now] = True
                val += 1
                now = p[now]
                
            ans += val*(val-1)//2
            #print(i,vis)
    
    print(ans)

    
    
        
        
        
        

if __name__ == '__main__':
    main()

提出情報

ジャッジ結果