Submission #7971444

---

Source Code Expand

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}

func getNextUint64(scanner *bufio.Scanner) uint64 {
	i, _ := strconv.ParseUint(getNextString(scanner), 10, 64)
	return i
}

func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}

func main() {
	fp := os.Stdin
	wfp := os.Stdout

	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
		if len(os.Args) > 2 {
			wfp, _ = os.Create(os.Args[2])
		}
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(wfp)

	n := getNextInt(scanner)
	m := getNextInt(scanner)

	nn := make([]int, n)
	mm := make([]int, m)

	for i := 0; i < n; i++ {
		nn[i] = i
	}

	for i := 0; i < m; i++ {
		mm[i] = -1
	}

	for i := 0; i < n; i++ {
		k := getNextInt(scanner)
		for ii := 0; ii < k; ii++ {
			l := getNextInt(scanner) - 1
			if mm[l] == -1 {
				mm[l] = i
				continue
			}

			r1 := root(i, nn)
			r2 := root(mm[l], nn)
			if r1 != r2 {
				nn[r2] = r1
			}
		}
	}

	counter := 0
	prev := -1

	ans := "YES"
	for i := 0; i < n; i++ {
		r := root(i, nn)
		if prev != r {
			prev = r
			counter++
			if counter > 1 {
				ans = "NO"
				break
			}
		}
	}

	fmt.Fprintln(writer, ans)
	writer.Flush()
}

func root(i int, nodes []int) int {
	if i == nodes[i] {
		return i
	}
	r := root(nodes[i], nodes)
	nodes[i] = r
	return nodes[i]
}

Submission Info

Judge Result