参考的输入挂，先挂在此处，以备以后使用。

import java.io.*;import java.util.*;import java.math.*; public class Main{     public static void main(String[] args)    {        InputReader in = new InputReader();        PrintWriter out = new PrintWriter(System.out);                                out.close();    }}class InputReader{    BufferedReader buf;    StringTokenizer tok;    InputReader()    {        buf = new BufferedReader(new InputStreamReader(System.in));    }    boolean hasNext()    {        while(tok == null || !tok.hasMoreElements())         {            try            {                tok = new StringTokenizer(buf.readLine());            }             catch(Exception e)             {                return false;            }        }        return true;    }    String next()    {        if(hasNext()) return tok.nextToken();        return null;    }    int nextInt()    {        return Integer.parseInt(next());    }    long nextLong()    {        return Long.parseLong(next());    }    double nextDouble()    {        return Double.parseDouble(next());    }    BigInteger nextBigInteger()    {        return new BigInteger(next());    }    BigDecimal nextBigDecimal()    {        return new BigDecimal(next());    }}

正确代码：

import java.io.*;import java.util.*;import java.math.*;public class Main{    public static void main(String[] args) {        InputReader in = new InputReader();        PrintWriter out = new PrintWriter(System.out);        final int maxn = 100000+10;        int[] vis = new int[maxn];        int n = in.nextInt(), num, flag = 0;        for(int i = 0; i < n; i++) {            num = in.nextInt();            if(vis[num] == 1)                flag = 1;            vis[num] = 1;        }        if(flag == 0)            out.println("NO");        else             out.println("YES");        out.close();    }}class InputReader{    BufferedReader buf;    StringTokenizer tok;    InputReader(){        buf = new BufferedReader(new InputStreamReader(System.in));    }    boolean hasNext() {        while(tok == null || !tok.hasMoreElements()) {            try {                tok = new StringTokenizer(buf.readLine());            }            catch(Exception e) {                return false;            }        }        return true;    }    String next() {        if(hasNext()) {            return tok.nextToken();        }        return null;    }    int nextInt() {        return Integer.parseInt(next());    }    long nextLong() {        return Long.parseLong(next());    }    double nextDouble() {        return Double.parseDouble(next());    }    BigInteger nextBigInteger() {        return new BigInteger(next());    }    BigDecimal nextBigDecimal() {        return new BigDecimal(next());    }}