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Weekly Report 2022.07

幸福如出一辙,不幸难觅一致

Combine theory and practice: Nothing works and don’t know why.

Reading

《经济常识一本通》

虽然不能说这本书的内容有多好,但是用来入门还是有一定效用的;也记录了一些笔记,以留后续速查。

Learning

旋转图像的两个途径

  • reverse upside down, then swap the symmetry
  • reverse left to right, then swap the symmetry
/*
 * clockwise rotate
 * first reverse up to down, then swap the symmetry
 * 1 2 3     7 8 9     7 4 1
 * 4 5 6  => 4 5 6  => 8 5 2
 * 7 8 9     1 2 3     9 6 3
*/
void rotate(vector<vector<int> > &matrix) {
    reverse(matrix.begin(), matrix.end());
    for (int i = 0; i < matrix.size(); ++i) {
        for (int j = i + 1; j < matrix[i].size(); ++j)
            swap(matrix[i][j], matrix[j][i]);
    }
}

/*
 * anticlockwise rotate
 * first reverse left to right, then swap the symmetry
 * 1 2 3     3 2 1     3 6 9
 * 4 5 6  => 6 5 4  => 2 5 8
 * 7 8 9     9 8 7     1 4 7
*/
void anti_rotate(vector<vector<int> > &matrix) {
    for (auto vi : matrix) reverse(vi.begin(), vi.end());
    for (int i = 0; i < matrix.size(); ++i) {
        for (int j = i + 1; j < matrix[i].size(); ++j)
            swap(matrix[i][j], matrix[j][i]);
    }
}

Centos8 Vault

由于 Centos8 已经进入 EOL 阶段,所以 yum/rpm 不能正常使用了。参考着 Tuna 的教程,更新了 yum 仓库的地址。

# CentOS 8
minorver=8.5.2111
sed -e "s|^mirrorlist=|#mirrorlist=|g" \
         -e "s|^#baseurl=http://mirror.centos.org/\$contentdir/\$releasever|baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/$minorver|g" \
         -i.bak \
         /etc/yum.repos.d/CentOS-*.repo
yum makecache

Life

现在的当下之急就是找到一个能够持之以恒向之奋斗的目标。

Quote

You may be morally and intellectually superior to everybody around you, but don’t try to make it too obvious unless you really intend to irritate somebody.

有效地关注重要之事。这样的智慧,因为反思、理解并欣赏生活而伟大,并不仅仅因为掌控生活而伟大。

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Reference

The older I get, the more I realize that most of life is a matter of what we pay attention to, of what we attend to [with focus].
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