题解 | 灵异背包？

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));

        int n = Integer.parseInt(br.readLine());
        String[] str = br.readLine().split("\\s+");

        long sum = 0;
        int minOdd = Integer.MAX_VALUE;

        for (String s : str) {
            int num = Integer.parseInt(s);

            sum += num;

            if ((num & 1) == 1) {
                minOdd = Math.min(num, minOdd);
            }
        }

        long res;

        if ((sum & 1) == 0) {
            res = sum;
        } else {
            if (minOdd != Integer.MAX_VALUE) {
                res = sum -
                      minOdd;// 总和是奇数，需要减去最小的奇数（若存在）
            } else {
                res = 0;// 没有奇数，只能选空背包
            }
        }
        out.println(res);
        out.flush();
        out.close();
        br.close();

    }
}