PE 78, not the nicest solution, bruteforcing on euler recurrence relation

projecteuler/078/main.cpp

@@ -0,0 +1,48 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+vector<long long> partition_function;
+
+long long partitioning(long long n){
+    long long result = 0;
+
+    for(long long k = 1; k <= n; ++k){
+        long long lower = n - k*(3 * k - 1) / 2;
+        long long upper = n - k*(3 * k + 1) / 2;
+        result = (result + (k % 2 == 0 ? -1 : 1) * ((upper >= 0 ? partition_function[upper] : 0) + (lower >=0 ? partition_function[lower] : 0))) % 1000000;
+    }
+
+    if(result < 0){
+        result += 1000000;
+    }
+
+    return result;
+}
+
+int main(){
+
+    cout << "Hello this is Patrick" << endl;
+    auto start = chrono::high_resolution_clock::now();
+
+    // Basically the same partitioning function as in PE 76
+
+    partition_function.push_back(1);
+
+    long long n = 1;
+    long long result = 1;
+
+    while(result != 0){
+        result = partitioning(n);
+        // cout << n << " ";
+        // cout << result << " ";
+        partition_function.push_back(result);
+        n++;
+    }
+
+    cout << n - 1 << endl;
+
+    auto duration = chrono::duration_cast<chrono::milliseconds>(chrono::high_resolution_clock::now() - start);
+    cout << (float)duration.count()/1000 << endl;
+    return 0;
+}