HDU 4708 Rotation Lock Puzzle

Rotation Lock Puzzle Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 659 Accepted Submission(s): 193     Problem Description Alice was felling into a cave. She found a strange door with a number square matrix. These numbers can be rotated around the center clockwise or counterclockwise. A fairy came and told her how to solve this puzzle lock: “When the sum of main diagonal and anti-diagonal is maximum, the door is open.”. Here, main diagonal is the diagonal runs from the top left corner to the bottom right corner, and anti-diagonal runs from the top right to the bottom left corner. The size of square matrix is always odd.         This sample is a square matrix with 5*5. The numbers with vertical shadow can be rotated around center ‘3’, the numbers with horizontal shadow is another queue. Alice found that if she rotated vertical shadow number with one step, the sum of two diagonals is maximum value of 72 (the center number is counted only once).   Input Multi cases is included in the input file. The first line of each case is the size of matrix n, n is a odd number and 3<=n<=9.There are n lines followed, each line contain n integers. It is end of input when n is 0 .   Output For each test case, output the maximum sum of two diagonals and minimum steps to reach this target in one line.   Sample Input 5 9 3 2 5 9 7 4 7 5 4 6 9 3 9 3 5 2 8 7 2 9 9 4 1 9 0   Sample Output 72 1   Source 2013 ACM/ICPC Asia Regional Online —— Warmup  

 
import java.io.*;  
import java.math.BigInteger;  
import java.util.*;  
  
public class Main {  
    BufferedReader bu;  
    PrintWriter pw;  
    int n;  
    int[][] a;  
  
    public static void main(String[] args) throws IOException {  
        new Main().work();  
    }  
  
    void work() throws IOException {  
        bu = new BufferedReader(new InputStreamReader(System.in));  
        pw = new PrintWriter(new OutputStreamWriter(System.out),true);  
        n = Integer.parseInt(bu.readLine());  
        while (n != 0) {  
            a = new int[n][n];  
            for (int i = 0; i < n; i++) {  
                String str[] = bu.readLine().split(" ");  
                for (int j = 0; j < n; j++) {  
                    a[i][j] = Integer.parseInt(str[j]);  
                }  
            }  
              
            BigInteger result = BigInteger.ZERO;  
            int step = 0;  
              
            for (int i = 0; i < n / 2; i++) {//控制圈數  
                BigInteger max = BigInteger.ZERO;  
                int temp = 0;  
                for (int j = i; j < n - 1 - i; j++) {  
                      
                    BigInteger sum = BigInteger.ZERO;  
                    sum = sum.add(BigInteger.valueOf(a[i][j]));//第i圈的 第一行順時針相加  
                    sum = sum.add(BigInteger.valueOf(a[n - 1 - i][n - 1 - j]));//第i圈的最後一行逆時針相加  
                    sum = sum.add(BigInteger.valueOf(a[j][n - 1 - i]));//第i圈的最後一列，順時針相加  
                    sum = sum.add(BigInteger.valueOf(a[n - 1 - j][i]));//第i圈的第一列，逆時針相加  
                    int flag = Math.min(Math.abs(j - i),Math.abs(j - (n - 1 - i)));//每次轉圈的最小步數  
                       
                    if (sum.compareTo(max) > 0) {  
                        max = sum;  
                        temp = flag;  
                    } else if (sum.compareTo(max) == 0 && temp > flag) {  
                        temp = flag;  
                    }  
  
                }  
                step += temp;  
                result = result.add(max);  
            }  
            result = result.add(BigInteger.valueOf(a[n / 2][n / 2]));//最後再加上中心元素  
            pw.println(result + " " + step);  
            n = Integer.parseInt(bu.readLine());  
        }  
    }  
}