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统计国家代号出现的次数,如果去的和来的相等就输出YES即可。
import java.util.*; public class Main10763 { public static void main(String[] args) { Scanner scan = new Scanner(System.in); while(true) { int n = scan.nextInt(); if(n == 0) break; int[] a = new int[500000], b = new int[500000]; Arrays.fill(a, 0); Arrays.fill(b, 0); int maxg = 0; for(int i=0; i<n; i++) { int mm = scan.nextInt(); int nn = scan.nextInt(); maxg = max(maxg, max(mm, nn)); a[mm] ++; b[nn] ++; } int cnt = 0; for(int i=0; i<=maxg; i++) { if(a[i] != b[i]) { cnt = 1; break; } } if(cnt == 0) System.out.println("YES"); else System.out.println("NO"); } } public static int max(int a, int b) { if(a >= b) return a; else return b; } }
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原文地址:http://blog.csdn.net/wxisme/article/details/42178277