import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int M = sc.nextInt();
        int[][] A = new int[N][M];
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < M; j++) {
                A[i][j] = sc.nextInt();
            }
        }
        int res = 0;
        for (int i = 0; i < M; i++) {
            int max = Integer.MIN_VALUE;
            for (int j = 0; j < N; j++) {
                max = Math.max(max, A[j][i]);
            }
            res += max;
        }
        System.out.println(res);
    }
}

第二题看是其他人发的帖子

import java.util.Arrays;
import java.util.Scanner;

public class Main2 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] nums = new int[n];
        for (int i = 0; i < n; i++)
            nums[i] = sc.nextInt();
        int sum = 0;
        int flag = 0;
        for (int i = 0; i < n; i++) {
            if (nums[i] < 0) {
                flag = 1;
            } else {
                sum += nums[i];
            }
        }
        if (flag == 1) {
            Arrays.sort(nums);
            int max = nums[nums.length - 1];
            sum -= max;
        }
        System.out.println(sum);
    }
}