introduce piggybanks_dfs

src/cw9/zad1/piggybanks_dfs.cpp

@@ -1,6 +1,39 @@
-// // inny pomysł: find-union
+/*
 
-// 0   1   2   3   4   5   6   7
-// 2   0   4   6   0   7   3   5
-// 0   1   0   3   0   5   3   5
-// +1                      +1  +1
+T(n) = O(n)
+M(n) = O(n)
+
+0   1   2   3   4   5   6   7
+2   0   4   6   0   7   3   5
+0   1   0   3   0   5   3   5
++1                      +1  +1
+*/
+
+#include <vector>
+
+int piggybanks_dfs(std::vector<int> piggybanks) {
+    std::vector<int> cycles(piggybanks.size(), -1);
+    int closed_cycles_count = 0;
+    int next_pig;
+    for (int i = 0; i < piggybanks.size(); i++) {
+        if (cycles[i] == -1) {
+            cycles[i] = i;
+            next_pig = piggybanks[i];
+            while (cycles[next_pig] == -1) {
+                cycles[next_pig] = i;
+                next_pig = piggybanks[next_pig];
+            }
+            if (next_pig == i) closed_cycles_count++;
+        }
+    }
+
+    return closed_cycles_count;
+}
+
+#include <iostream>
+
+int main() {
+    std::cout << piggybanks_dfs({2, 0, 4, 6, 0, 7, 3, 5});
+}
+
+// inny pomysł: find-union