[HackerRank] Diagonal Difference

最新推荐文章于 2025-08-11 20:54:36 发布

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原文链接：https://segmentfault.com/a/1190000005596094

文章标签：

#java

本文介绍了一种计算矩阵两条对角线元素之和的绝对差的方法。输入为一个N×N的矩阵，输出为两个对角线元素之和的绝对差值。

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Problem

Given a square matrix of size N x N, calculate the absolute difference between the sums of its diagonals.

Input Format

The first line contains a single integer, N. The next N lines denote the matrix's rows, with each line containing N space-separated integers describing the columns.

Output Format

Print the absolute difference between the two sums of the matrix's diagonals as a single integer.

Sample Input

3

11    2     4
4     5     6
10    8     -12

Sample Output

Explanation

The primary diagonal is:

11
      5
            -12

Sum across the primary diagonal: 11 + 5 - 12 = 4

The secondary diagonal is:

            4
      5
10

Sum across the secondary diagonal: 4 + 5 + 10 = 19
Difference: |4 - 19| = 15

Solution

import java.io.*;
import java.util.*;
public class Solution {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int pSum = 0, sSum = 0;
        int a[][] = new int[n][n];
        for(int i = 0; i < n; i++){
            for(int j = 0; j < n; j++){
                a[i][j] = in.nextInt();
            }
        }
        for(int i=0; i<n; i++){
            pSum += a[i][i];
            sSum += a[i][n-1-i];
        }
        int sum = Math.abs(pSum - sSum);
        System.out.println(sum);
    }
}