PE 075, pretty neat

projecteuler/075/main.cpp

@@ -0,0 +1,56 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int gcd(const int a, const int b){
+    if(b == 0){
+        return a;
+    }
+
+    return gcd(b, a % b);
+}
+
+int main(){
+
+    cout << "Hello this is Patrick" << endl;
+    auto start = chrono::high_resolution_clock::now();
+
+    // Generating pythagorean triplets can be done with Euclid's formula
+
+    int maxLength = 1500000;
+    vector<int> occurrences(maxLength + 1, 0);
+
+    for(int i = 1; i < 1500; ++i){
+        for(int j = 1; j < i; ++j){
+            if(gcd(i, j) != 1 || ((i % 2) != 0 && (j % 2) != 0)){
+                continue;
+            }
+
+            for(int k = 1; k < maxLength / i; ++k){
+                long a = k * (i*i - j*j);
+                long b = 2 * k * i * j;
+                long c = k * (i*i + j*j);
+
+                long l = a + b + c;
+
+                if(l < occurrences.size()){
+                    occurrences[l]++;
+                    // cout << a << " " << b << " " << c << " " << l << endl;
+                }
+            }
+        }
+    }
+
+    int result = 0;
+    for(auto o : occurrences){
+        if(o == 1){
+            result++;
+        }
+    }
+
+    cout << result << endl;
+
+    auto duration = chrono::duration_cast<chrono::milliseconds>(chrono::high_resolution_clock::now() - start);
+    cout << (float)duration.count()/1000 << endl;
+    return 0;
+}