Combine theory and practice: Nothing works and don’t know why.
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Reading
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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。
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Learning
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旋转图像的两个途径
- reverse upside down, then swap the symmetry
- reverse left to right, then swap the symmetry
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/*
* 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]);
}
}
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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。
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# 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
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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。
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Quotation
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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Recommendation
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References
