提出 #32170193

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ソースコード 拡げる

class UnionFind:
    def __init__(self, n):
        self.par = [i for i in range(n)]
        self.siz = [1] * n
    def root(self, x):
        if self.par[x] == x:
            return x
        self.par[x] = self.root(self.par[x]) # 経路圧縮
        return self.par[x]
    def unite(self, x, y):
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return
        if self.siz[x] > self.siz[y]: # マージテク
            self.par[y] = x
            self.siz[x] += self.siz[y]
        else:
            self.par[x] = y
            self.siz[y] += self.siz[x]
    def is_same(self, x, y):
        return self.root(x) == self.root(y)
    def size(self, x):
        return self.siz[self.root(x)]
n = int(input())
a = list(map(int, input().split()))
uf = UnionFind(200001)
answer = 0
for i in range(n):
    if not uf.is_same(a[i], a[n - 1 - i]):
        uf.unite(a[i], a[n - 1 - i])
        answer += 1
print(answer)

提出情報

ジャッジ結果