提出 #52603101

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ソースコード 拡げる

fun main() {
    val (n, m) = readln().split(" ").map { it.toInt() }

    val uf = UnionFind(n + 1)
    val ab = List(m) {
        val (a, b) = readln().split(" ").map { it.toInt() }
        uf.union(a, b)

        a to b
    }

    val bucket = IntArray(n + 1)
    val set = mutableSetOf<Int>()
    for(i in 1..n) {
        val root = uf.find(i)
        set.add(root)

        bucket[root]++
    }

    var ans = 0L
    var diff = 0
    for(root in set) {
        val count = bucket[root].toLong()
        if(count < 3) {
            if(count == 2L) {
                diff++
            }

            continue
        }

        val ideal = count * (count - 1) / 2
        ans += ideal
    }

    println(ans - (m - diff))
}

private class UnionFind(n: Int) {
    private val roots = IntArray(n) { it }
    private val ranks = IntArray(n) { 1 }

    fun find(i: Int): Int {
        if(roots[i] != i) {
            roots[i] = find(roots[i])
        }

        return roots[i]
    }

    fun isSame(x: Int, y: Int): Boolean {
        return find(x) == find(y)
    }

    fun union(x: Int, y: Int) {
        val rootX = find(x)
        val rootY = find(y)

        if(rootX == rootY) {
            return
        }
        if(ranks[rootX] > ranks[rootY]) {
            roots[rootY] = rootX
            ++ranks[rootX]
        } else {
            roots[rootX] = rootY
            ++ranks[rootY]
        }
    }
}

提出情報

コンパイルエラー

Main.kt:5:9: warning: variable 'ab' is never used
    val ab = List(m) {
        ^

ジャッジ結果