freckles solution

freckles/main.cpp

@@ -0,0 +1,90 @@
+/*
+ * @AUTHOR: Hugo Cedervall
+ * @DATE: 2021-03-04
+ * @PROBLEM: freckles
+*/
+
+#include <bits/stdc++.h>
+#include <iostream>
+
+using namespace std;
+
+
+struct Edge {
+    pair<double, double> from, to;
+    double distance;
+
+    Edge(pair<double, double> from, pair<double, double> to) {
+        this->from = from, this->to = to;
+        // Euclidean distance between given nodes
+        this->distance = sqrt(pow(from.first - to.first, 2) + pow(from.second - to.second, 2));
+    }
+
+    bool operator<(const Edge &e) const {
+        if (distance == e.distance) return from > e.from;
+        return distance > e.distance;
+    }
+};
+
+/*
+ * Prim's Minimul Spanning Tree algorithm
+ */
+double solution(vector<pair<double, double>> bridePos) {
+    priority_queue<Edge> q;
+
+    // Choose arbitary node to start with
+    auto start = bridePos[0];
+
+    // Path betweeen start and brideopenings
+    for (auto b1 : bridePos) {
+        q.push(Edge{start, b1});
+    }
+
+    map<pair<double, double>, bool> marked;
+    double totalDistance = 0;
+    while (!q.empty()) {
+        auto curr = q.top();
+        q.pop();
+
+        // Choose node only if outgoing is not already marked
+        if (!marked[curr.to]) {
+            marked[curr.to] = true;
+            totalDistance += curr.distance;
+
+            // For each connected which is not already marked
+            for (auto &p : bridePos) {
+                if (!marked[p]) {
+                    q.push(Edge{curr.to, p});
+                }
+            }
+        }
+    }
+    return totalDistance;
+}
+
+int main() {
+    ios::sync_with_stdio(false);
+    cin.tie(NULL);
+
+    // Insert code here
+    int cases;
+    cin >> cases;
+    int n;
+    double a, b;
+    while (cases--) {
+        cin >> n;
+        vector<pair<double, double>> bridgePos(n);
+        for (int j = 0; j < n; ++j) {
+            cin >> a >> b;
+            bridgePos[j] = make_pair(a, b);
+        }
+
+        double res = solution(bridgePos);
+        cout << fixed << setprecision(2) << res << '\n';
+
+    }
+    cout << flush;
+
+
+    return 0;
+}