pairup

contests/silver/2017/usopen/pairup.cpp

@@ -0,0 +1,50 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+#define MAX_N 1e5
+
+struct Cow
+{
+  int time, num;
+};
+
+vector<Cow> cows(MAX_N);
+int main() 
+{
+  ifstream fin("pairup.in");
+  ofstream fout("pairup.out");
+
+  int N;
+  fin >> N;
+
+  for (int i = 0; i < N; ++i)
+    fin >> cows[i].num >> cows[i].time;
+
+  sort(cows.begin(), cows.begin() + N, [](const Cow &a, const Cow &b)
+  { return a.time < b.time; });
+
+  int p1 = 0, p2 = N - 1, maxPair = 0;
+  while (p1 <= p2)
+  {
+    maxPair = max(maxPair, cows[p1].time + cows[p2].time);
+
+    // skip the rest of calculations between p1 and p2, as they will always
+    // be the same as the current sum
+    if (cows[p1].num < cows[p2].num)
+    {
+      cows[p2].num -= cows[p1].num;
+      ++p1;
+    }
+    else if (cows[p2].num < cows[p1].num)
+    {
+      cows[p1].num -= cows[p2].num;
+      --p2;
+    }
+    else ++p1, --p2;
+  }
+
+
+  fout << maxPair << '\n';
+
+  return 0;
+}

contests/silver/2017/usopen/pairup.in

@@ -0,0 +1,4 @@
+3
+1 8
+2 5
+1 2

contests/silver/2017/usopen/pairup.out

@@ -0,0 +1 @@
+10