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Merge branch 'master' of https://github.com/thecodingwizard/usaco-guide

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Benjamin Qi 2020-06-28 21:18:02 -04:00
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2
content/1_Intro/Data_Types.md
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@ -18,7 +18,7 @@ There are several main **data types** that are used in contests: 64-bit integers
It's a good idea to use 64-bit integers (`long long` in C++) instead of 32-bit integers (`int`). 64-bit integers are less likely to have overflow issues, since they can store any number between $-9\,223\,372\,036\,854\,775\,808$ and $9\,223\,372\,036\,854\,775\,807$ which is roughly equal to $\pm 9 \times 10^{18}$. Contest problems are usually set such that the 64-bit integer is sufficient. Of course, you shouldn't do this when time and/or memory limits are tight, which may be the case in higher divisions of USACO.
**Floating point numbers** are used to store decimal values. It is important to know that floating point numbers are not exact, because the binary architecture of computers can only store decimals to a certain precision. Hence, we should always expect that floating point numbers are slightly off. Contest problems will accommodate this by either asking for the greatest integer less than $10^k$ times the value, or will mark as correct any output that is within a certain $\epsilon$ of the judge's answer. (what's epsilon?)
**Floating point numbers** are used to store decimal values. It is important to know that floating point numbers are not exact, because the binary architecture of computers can only store decimals to a certain precision. Hence, we should always expect that floating point numbers are slightly off. Never try to compare two floating-point numbers for exact equality (==); instead, check if their absolute difference is less than some small constant like $10^{-9}$. Contest problems will accommodate this by either asking for the greatest integer less than $10^k$ times the value, or will mark as correct any output that is within a certain $\epsilon$ of the judge's answer. (what's epsilon?)
**Boolean** variables have two possible states: `true` and `false`. We'll usually use booleans to mark whether a certain process is done, and arrays of booleans to mark which components of an algorithm have finished.

38
content/1_Intro/Input_Output.md
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@ -21,7 +21,7 @@ In most websites (such as CodeForces and CSES), input and output are **standard*
### C++
The [<iostream\>](http://www.cplusplus.com/reference/iostream/) library suffices.
The [<iostream\>](http://www.cplusplus.com/reference/iostream/) library suffices.
```cpp
#include <iostream>
@ -33,9 +33,35 @@ int main() {
}
```
Alternatively, you can use the [<cstdio\>](http://www.cplusplus.com/reference/cstdio/) library's `scanf` anf `printf` functions, which are slightly more complicated to use, but are significantly faster (generally only an issue with large input sizes):
```cpp
#include <cstdio>
using namespace std;
int main() {
int x, y;
// %d specifies that a value of type int is being input.
// Use %lld (a few judging platforms might need %I64d)
// to input a long long (64-bit) integer.
// Many other specifiers are also available; see link for more details.
// Be sure to add a & character (address-of operator) when using
// scanf, UNLESS you are inputing a string with %s.
// It is possible to input multiple values at a time as shown below.
scanf("%d%d", &x, &y);
// Specifiers for printf are mostly the same as those used
// by scanf, with the notable exception of floating-point numbers.
// Use a backslash character followed by the lowercase
// letter n to denote a newline.
// The address-of operator, &, is not used here.
printf("Found %d and %d\n", x, y);
}
```
### Java
In your CS classes, you've probably implemented input and output using standard input and standard output, or using [`Scanner`](https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html) to read input and `System.out.print` to print output. These methods work, but `Scanner` and `System.out.print` are slow when we have to handle inputting and outputting tens of thousands of lines. Thus, we use `BufferedReader` and `PrintWriter` instead, which are faster because they buffer the input and output and handle it all at once as opposed to parsing each line individually.
In your CS classes, you've probably implemented input and output using standard input and standard output, or using [`Scanner`](https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html) to read input and `System.out.print` to print output. These methods work, but `Scanner` and `System.out.print` are slow when we have to handle inputting and outputting tens of thousands of lines. Thus, we use `BufferedReader` and `PrintWriter` instead, which are faster because they buffer the input and output and handle it all at once as opposed to parsing each line individually.
Here is a Java template for input and output, which is effectively a faster Scanner. We import the entire `util` and `io` libraries for ease of use.
@ -114,11 +140,11 @@ In order to test a program, create a file called `problemname.in`, and then run
## C++
You will need the [<cstdio\>](http://www.cplusplus.com/reference/cstdio/) or the [<fstream\>](http://www.cplusplus.com/reference/fstream/) library. Essentially, replace every instance of the word `problemname` in the word below with the input/output file name, which should be given in the problem.
You will need the [<cstdio\>](http://www.cplusplus.com/reference/cstdio/) or the [<fstream\>](http://www.cplusplus.com/reference/fstream/) library. Essentially, replace every instance of the word `problemname` in the word below with the input/output file name, which should be given in the problem.
Below, we have included C++ templates for input and output. We use `using namespace std;` so that we don't have to preface standard library functions with `std::` each time we use them.
If `<cstdio>` is used:
If `<cstdio>` is used:
```cpp
#include <cstdio>
@ -131,7 +157,7 @@ int main() {
}
```
If `<fstream>` is used: (Note that you cannot use C-style I/O (`scanf`, `printf`) with this method):
If `<fstream>` is used: (Note that you cannot use C-style I/O (`scanf`, `printf`) with this method):
```cpp
#include <fstream>
@ -194,7 +220,7 @@ public class template {
PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter("template.out")));
// YOUR CODE HERE
pw.close(); // flushes the output once printing is done
}
}

0
content/1_Intro/Running_Cpp.md → content/1_Intro/Running_Cpp.mdx
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1
content/6_Plat/HLD.mdx
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@ -24,6 +24,7 @@ export const metadata = {
new Problem("HR", "Subtrees & Paths", "https://www.hackerrank.com/challenges/subtrees-and-paths", "Easy", false, ["HLD"], ""),
new Problem("CF", "Tree Queries", "contest/1254/problem/D", "Normal", false, ["HLD"], ""),
new Problem("ojuz", "JOI - Cats or Dogs", "https://oj.uz/problem/view/JOI18_catdog", "Hard", false, ["HLD"], ""),
new Problem("wcipeg", "COI 08-Otoci", "https://wcipeg.com/problem/coi08p2", "Hard", false, ["HLD"], "editorial available online"),
],
}
};

48
src/components/markdown/Resources.tsx
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@ -2,31 +2,33 @@ import * as React from 'react';
import Dots from '../Dots';
export function ResourcesListComponent(props) {
const embedded = props.embedded;
return (
<div className="flex flex-col">
<div className="-my-2 py-2 overflow-x-auto sm:-mx-6 sm:px-6 lg:-mx-8 lg:px-8">
<div className="align-middle inline-block min-w-full shadow overflow-hidden sm:rounded-lg border border-purple-400">
<div
className={`overflow-x-auto ${
embedded
? '-mx-4 sm:-mx-6'
: 'sm:-mx-6 sm:px-6 lg:-mx-8 lg:px-8 -my-2 py-2'
}`}
>
<div
className={`align-middle inline-block min-w-full overflow-hidden shadow ${
!embedded && 'rounded-lg border border-purple-400'
}`}
>
<table className="min-w-full">
<thead>
<tr>
<th
colSpan={4}
className="px-6 py-4 border-b border-purple-200 bg-purple-50 text-left font-medium text-purple-500 uppercase"
className={`px-6 border-b text-left font-medium uppercase ${
embedded
? 'text-sm py-2 border-gray-200 bg-gray-50 text-gray-500'
: 'py-3 border-purple-200 bg-purple-50 text-purple-500'
}`}
>
<div className="flex items-center">
<svg
fill="none"
strokeLinecap="round"
strokeLinejoin="round"
strokeWidth="2"
viewBox="0 0 24 24"
stroke="currentColor"
className="h-6 w-6 mr-3"
>
<path d="M5 5a2 2 0 012-2h10a2 2 0 012 2v16l-7-3.5L5 21V5z" />
</svg>
Resources{props.title ? `: ${props.title}` : ''}
</div>
Resources{props.title ? `: ${props.title}` : ''}
</th>
</tr>
</thead>
@ -70,10 +72,12 @@ export function ResourceComponent(props) {
}
return (
<tr>
<td className="px-6 py-4 whitespace-no-wrap text-sm leading-5 text-gray-500">
{props.source}
</td>
<td className="py-4 whitespace-no-wrap text-sm leading-5 text-gray-500 w-6">
{props.source && (
<td className="pl-6 py-4 whitespace-no-wrap text-sm leading-5 text-gray-500">
{props.source}
</td>
)}
<td className="pl-6 py-4 whitespace-no-wrap text-sm leading-5 text-gray-500 w-6">
{props.starred && (
<svg
className="h-6 w-6 text-blue-700"
@ -87,7 +91,7 @@ export function ResourceComponent(props) {
<td className="pl-3 pr-6 py-4 whitespace-no-wrap text-sm leading-5 font-medium text-gray-900">
<a href={url}>{props.title}</a>
</td>
<td className="px-6 py-4 whitespace-no-wrap text-sm leading-5 text-gray-500">
<td className="w-100 px-6 py-4 text-sm leading-5 text-gray-500">
{props.children}
</td>
</tr>