java - 从左上到右下对角读取矩阵的所有元素

Question

我有一个java代码，可以从右上到左下读取对角线值，但我希望代码从左上到右下读取值。

int [][]mat = { {1,2,3},
                {4,5,6},
                {7,8,9},
};

int N=3;

for (int s=0; s<N; s++) {
    for (int i=s; i>-1; i--) {
        System.out.print(mat[i][s-i] + " ");
    }
    System.out.println();
}

for (int s=1; s<N; s++) {
    for (int i=N-1; i>=s; i--) {
        System.out.print(mat[i][s+N-1-i] + " ");
    }
    System.out.println();
}

上面代码的输出是

1 4 2 7 5 3 8 6 9

我想要像这样的序列

3 2 6 1 5 9 4 8 7

Answer 1

int [][]mat = { {1,2,3},
                {4,5,6},
                {7,8,9},
};

int N=3;

for (int s=N-1; s>-N; --s) {
    int iMin = s>0 ? s : 0;
    int iMax = s>0 ? N : N+s;
    for (int i=iMin; i<iMax; ++i) {
        System.out.print(mat[i-s][i] + " ");
    }
}
System.out.println();

输出

3 2 6 1 5 9 4 8 7