chore: import upstream snapshot with attribution

graph/kruskal.cpp

@@ -0,0 +1,64 @@
+#include <algorithm>
+#include <array>
+#include <iostream>
+#include <vector>
+//#include <boost/multiprecision/cpp_int.hpp>
+// using namespace boost::multiprecision;
+const int mx = 1e6 + 5;
+using ll = int64_t;
+
+std::array<ll, mx> parent;
+ll node, edge;
+std::vector<std::pair<ll, std::pair<ll, ll>>> edges;
+void initial() {
+    for (int i = 0; i < node + edge; ++i) {
+        parent[i] = i;
+    }
+}
+
+int root(int i) {
+    while (parent[i] != i) {
+        parent[i] = parent[parent[i]];
+        i = parent[i];
+    }
+    return i;
+}
+
+void join(int x, int y) {
+    int root_x = root(x);  // Disjoint set union by rank
+    int root_y = root(y);
+    parent[root_x] = root_y;
+}
+
+ll kruskal() {
+    ll mincost = 0;
+    for (int i = 0; i < edge; ++i) {
+        ll x = edges[i].second.first;
+        ll y = edges[i].second.second;
+        if (root(x) != root(y)) {
+            mincost += edges[i].first;
+            join(x, y);
+        }
+    }
+    return mincost;
+}
+
+int main() {
+    while (true) {
+        int from = 0, to = 0, cost = 0, totalcost = 0;
+        std::cin >> node >> edge;  // Enter the nodes and edges
+        if (node == 0 && edge == 0) {
+            break;  // Enter 0 0 to break out
+        }
+        initial();  // Initialise the parent array
+        for (int i = 0; i < edge; ++i) {
+            std::cin >> from >> to >> cost;
+            edges.emplace_back(make_pair(cost, std::make_pair(from, to)));
+            totalcost += cost;
+        }
+        sort(edges.begin(), edges.end());
+        std::cout << kruskal() << std::endl;
+        edges.clear();
+    }
+    return 0;
+}