Merge pull request #364 from Mastermind497/master

content: add cpp implementation to feb17-maxcross

Author: bqi343

solutions/USACO feb17-maxcross.mdx

@@ -1,16 +1,62 @@
 ---
 id: usaco-715
 title: USACO Feb 2017 Silver - Why Did the Cow Cross the Road II
-author: Mrinall Umasudhan
+author: Mrinall Umasudhan, Shourya Bansal
 ---
 
-Official Editorial: http://www.usaco.org/index.php?page=viewproblem2&cpid=715
+[Original Problem](http://www.usaco.org/index.php?page=viewproblem2&cpid=715)
 
-### Implementation
+[Official Analysis](http://www.usaco.org/current/data/sol_maxcross_silver_feb17.html)
 
 <LanguageSection>
+<CPPSection>
+
+## C++ Implementation
+
+```cpp
+#include <bits/stdc++.h>
+using namespace std;
+
+int main() {
+    freopen("maxcross.in", "r", stdin);
+    freopen("maxcross.out", "w", stdout);
+    
+    int N, K, B;
+    cin >> N >> K >> B;
+
+    // Use vector because it defaults to 0
+    vector<bool> status(N + 1);
+
+    // Converts all broken lights to 1 in vector
+    for (int i = 0; i < B; i++) {
+        int broken;
+        cin >> broken;
+
+        status[broken] = 1;
+    }
+
+    // Calculates the Prefix Sum of the broken lights
+    vector<int> prefix(N + 1);
+    for (int i = 1; i <= N; i++) {
+        prefix[i] = prefix[i - 1] + status[i];
+    }
+
+    // Finds a range of K traffic lights with the minimum broken ones
+    int broken = K;
+    for (int i = K; i <= N; i++) {
+        broken = min(broken, prefix[i] - prefix[i - K]);
+    }
+
+    cout << broken << '\n';
+    return 0;
+}
+```
+
+</CPPSection>
 <JavaSection>
 
+## Java Implementation
+
 ```java
 import java.io.*;
 import java.util.*;
@@ -91,5 +137,3 @@ public class maxcross {
 
 </JavaSection>
 </LanguageSection>
-
-