Merge pull request #3235 from cpinitiative/ryanchou-dev-patch-21

so tell me, am i crazy?

Author: SansPapyrus683

solutions/usaco-713.mdx

@@ -2,11 +2,148 @@
 id: usaco-713
 source: USACO Bronze 2017 February
 title: Why Did the Cow Cross the Road III
-author: Óscar Garries, Ryan Chou
+author: Óscar Garries, Ryan Chou, Varun Ragunath
 ---
 
 [Official Analysis (Java)](http://www.usaco.org/current/data/sol_cowqueue_bronze_feb17.html)
 
+## Video Solution
+
+By Varun Ragunath
+
+<Youtube id="O7r-Tp9vFGQ" />
+
+<Spoiler title="Video Solution Code">
+<LanguageSection>
+<CPPSection>
+
+```cpp
+#include<bits/stdc++.h>
+using namespace std;
+
+int main() {
+	freopen("cowqueue.in", "r", stdin);
+	freopen("cowqueue.out", "w", stdout);
+	cin.sync_with_stdio(0); cin.tie(0);
+
+	// get input
+	// number of cows, information for each cow
+
+	int n;
+	cin >> n;
+
+	vector<pair<int, int>> cows(n);
+
+	for(int i = 0; i < n; i++) {
+		cin >> cows[i].first >> cows[i].second;
+	}
+
+	// now we need to determine the optimal ordering
+	// obviously sorting is the "best" and only way to sort the cows
+
+	// to sort the cows we can either use a library implementation or bubble sort
+
+	// here we will implement bubble sort
+
+	bool swapped = true;
+
+	while(swapped) {
+		swapped = false;
+		for(int i = 0; i < n - 1; i++) {
+			if(cows[i] > cows[i + 1]) {
+				swap(cows[i], cows[i + 1]);
+				swapped = true;
+			}
+		}
+	}
+
+	// now that we have sorted the array, it is time to simulate the process
+
+	int cur_time = 0; // stores the current time
+
+	for(int i = 0; i < n; i++) {
+		// if the time the current cow we are processing has already passed
+		// then we need to update their time to the current time
+		cows[i].first = max(cows[i].first, cur_time);
+		// now we need to calculate when they will be able to leave the questioning
+		cur_time = cows[i].first + cows[i].second;
+		// cur_time now holds the amount of time needed to process the first i cows
+	}
+
+	cout << cur_time << '\n';
+
+	return 0;
+}
+```
+
+</CPPSection>
+<JavaSection>
+
+```java
+import java.io.*;
+import java.util.*;
+
+public class cowqueue{
+	public static void main(String[] args) throws IOException{
+		cowqueue.Kattio io = new cowqueue.Kattio("cowqueue");
+
+		// getting input
+		// number of cows, information for each cow
+		int n = io.nextInt();
+		int[][] cows = new int[n][2];
+
+		for(int i = 0; i < n; i++) {
+			for(int j = 0; j < 2; j++) {
+				cows[i][j] = io.nextInt();
+			}
+		}
+
+		// we need to generate the optimal ordering of cows
+		// clearly the optimal ordering will be to just sort the cows by arriving time
+		// we can do bubble sort 
+
+		boolean swapped = true;
+
+		while(swapped) {
+			swapped = false;
+			for(int i = 0; i < n - 1; i++) {
+				if(cows[i][0] > cows[i + 1][0]) {
+				// how do you write a swap in java????
+				int ext = cows[i][0];
+				cows[i][0] = cows[i + 1][0];
+				cows[i + 1][0] = ext;
+
+				ext = cows[i][1];
+				cows[i][1] = cows[i + 1][1];
+				cows[i + 1][1] = ext;
+				
+				swapped = true;
+				}
+			}
+		}
+
+		// now it is time to simulate the process
+		int cur_time = 0; // stores the current time
+
+		for(int i = 0; i < n; i++) {
+		// update the time cow[i] starts questioning
+		cows[i][0] = Math.max(cur_time, cows[i][0]);
+		// now that we have the time ith cow enters the queue,
+		// lets calculate when it leaves the queue
+		cur_time = (cows[i][0] + cows[i][1]);
+		}
+
+		io.println(cur_time);
+		io.close();
+	}
+
+	//CodeSnip{Kattio}
+}
+```
+</JavaSection>
+</LanguageSection>
+</Spoiler>
+	
 Since the time the cows arrive and need for questioning can be up to $10^6$, we should traverse through the times as steps.
 
 ## Implementation