Finished beads and milk2 for usaco

usaco/ch1/beads.cpp

@@ -7,9 +7,12 @@ LANG: C++
 #include <iostream>
 #include <fstream>
 #include <string>
+#include <algorithm>
 
 using namespace std;
 
+enum Colour{ red, blue, white };
+
 int main() {
     ofstream fout ("beads.out");
     ifstream fin ("beads.in");
@@ -19,7 +22,95 @@ int main() {
     
     fin >> n >> s;
 
-    
+    string doubleNecklace = s.append(s);
+
+    Colour lastBead = white, prewhiteBead = white;
+    int currentLength = 0, redLength = 0, blueLength = 0, longestChain = 0, preWhiteLength = 0, inbetweenWhiteLength = 0;
+
+    // The most intricate scenario is the following scenario:
+    // white - red - white - blue - white
+    // or equivalently:
+    // white - blue - white - red - white
+
+    // When white beads are enclosed by beads of the same colour we regard the beads as those colour
+
+
+    for(const char& bead : doubleNecklace){
+        if(bead == 'w'){
+            if(lastBead == white){
+                currentLength++;
+            } else if(lastBead == red){
+                prewhiteBead = red;
+                redLength = currentLength;
+                currentLength = 1;
+            } else{ // Last bead is blue
+                prewhiteBead = blue;
+                blueLength = currentLength;
+                currentLength = 1;
+            }
+            longestChain = max(longestChain, currentLength + redLength + blueLength + prewhiteBead + inbetweenWhiteLength);
+            lastBead = white;
+
+        } else if(bead == 'r'){
+            if(lastBead == red){
+                currentLength++;
+                longestChain = max(longestChain, currentLength + preWhiteLength + blueLength + inbetweenWhiteLength);
+            } else if(lastBead == blue){
+                longestChain = max(longestChain, currentLength + redLength + preWhiteLength + inbetweenWhiteLength);
+                blueLength = currentLength;
+                redLength = 0;
+                currentLength = 1;
+                preWhiteLength = inbetweenWhiteLength;
+                inbetweenWhiteLength = 0;
+            } else{ // Last bead is white
+                if(prewhiteBead == red){
+                    currentLength += redLength + 1;
+                    redLength = 0;
+                    longestChain = max(longestChain, currentLength + preWhiteLength + blueLength + inbetweenWhiteLength);
+                } else{
+                    longestChain = max(longestChain, currentLength + blueLength + redLength + preWhiteLength + inbetweenWhiteLength);
+                    preWhiteLength = inbetweenWhiteLength;
+                    inbetweenWhiteLength = currentLength;
+                    redLength = 0;
+                    currentLength = 1;
+                }
+            }
+            lastBead = red;
+
+        } else if(bead == 'b'){
+            if(lastBead == blue){
+                currentLength++;
+                longestChain = max(longestChain, currentLength + redLength + preWhiteLength + inbetweenWhiteLength);
+            } else if(lastBead == red){
+                longestChain = max(longestChain, currentLength + blueLength + preWhiteLength + inbetweenWhiteLength);
+                redLength = currentLength;
+                blueLength = 0;
+                currentLength = 1;
+                preWhiteLength = inbetweenWhiteLength;
+                inbetweenWhiteLength = 0;
+            } else{ // Last bead is white
+                if(prewhiteBead == blue){
+                    currentLength += blueLength + 1;
+                    blueLength = 0;
+                    longestChain = max(longestChain, currentLength + redLength + preWhiteLength + inbetweenWhiteLength);
+                } else{
+                    longestChain = max(longestChain, currentLength + blueLength + redLength + preWhiteLength + inbetweenWhiteLength);
+                    preWhiteLength = inbetweenWhiteLength;
+                    inbetweenWhiteLength = currentLength;
+                    blueLength = 0;
+                    currentLength = 1;
+                }
+            }
+            lastBead = blue;
+
+        } else{
+            cout << "unexpected input" << endl;
+            return 0;
+        }
+        // cout << bead << " CurrentLength: " << currentLength << " RedLength: " << redLength << " BlueLength: " << blueLength << " Prewhitelength: " << preWhiteLength << " Inbetweenwhite: " << inbetweenWhiteLength << " LongestChain: " << longestChain << endl;
+    }
+
+    fout << min(longestChain, int(s.size()) / 2) << endl;
 
     return 0;
 }

usaco/ch1/milk2.cpp

@@ -0,0 +1,73 @@
+/*
+ID: philipp17
+PROG: milk2
+LANG: C++                 
+*/
+/* LANG can be C++11 or C++14 for those more recent releases */
+#include <iostream>
+#include <fstream>
+#include <string>
+#include <vector>
+#include <utility>
+#include <algorithm>
+
+using namespace std;
+
+bool sorter(const pair<int, bool>& i, const pair<int, bool>& j){
+    if(i.first != j.first){
+        return (i.first < j.first);
+    }
+
+    return (i.second > j.second);
+}
+
+int main() {
+    ofstream fout ("milk2.out");
+    ifstream fin ("milk2.in");
+
+    int n;
+    fin >> n;
+
+    vector<pair<int, bool>> events(2 * n);
+    for(int i = 0; i < n; ++i){
+        int start, end;
+        fin >> start >> end;
+
+        events[2 * i] = {start, true};
+        events[2 * i+1] = {end, false};
+    }
+
+    sort(events.begin(), events.end(), sorter);
+
+    int longestMilking = 0, longestIdle = 0, milkers = 0, startMilking = -1, endMilking = -1;
+
+    for(auto e : events){
+        if(e.second){ // So it is time to milk
+            if(milkers == 0 && endMilking != -1){
+                longestIdle = max(longestIdle, e.first - endMilking);
+            } if(milkers == 0){
+                startMilking = e.first;
+            }
+            milkers++;
+        }
+
+        else{ // So milking is stopped somewhere
+            milkers--;
+
+            if(milkers == 0 && startMilking != -1){
+                longestMilking = max(longestMilking, e.first - startMilking);
+            } if(milkers == 0){
+                endMilking = e.first;
+            }
+        }
+        // cout << e.second << " " << e.first << " " << milkers << " " << startMilking << " " << endMilking << " " << longestMilking << " " << longestIdle << endl;
+    }
+
+    fout << longestMilking << " " << longestIdle << endl;
+
+    // for(auto e : events){
+    //     cout << e.first << " " << e.second << endl;
+    // }
+
+    return 0;
+}