Added c++ solution for 2000-2099 / 2097. Valid Arrangement of Pair

Author: ZAID646

solution/2000-2099/2097.Valid Arrangement of Pairs/Solutions.cpp

@@ -0,0 +1,48 @@
+#include <vector>
+#include <unordered_map>
+#include <stack>
+using namespace std;
+
+class Solution {
+public:
+    vector<vector<int>> validArrangement(vector<vector<int>>& pairs) {
+        unordered_map<int, stack<int>> graph;
+        unordered_map<int, int> out_degree;
+        
+        for (auto& p : pairs) {
+            graph[p[0]].push(p[1]);
+            out_degree[p[0]]++;
+            out_degree[p[1]]--;
+        }
+        
+        int start = pairs[0][0];
+        for (auto& [node, degree] : out_degree) {
+            if (degree > 0) {
+                start = node;
+                break;
+            }
+        }
+        
+        vector<vector<int>> result;
+        stack<int> path;
+        path.push(start);
+        
+        while (!path.empty()) {
+            int current = path.top();
+            if (!graph[current].empty()) {
+                path.push(graph[current].top());
+                graph[current].pop();
+            } else {
+                if (path.size() > 1) {
+                    int end = path.top(); path.pop();
+                    result.push_back({path.top(), end});
+                } else {
+                    path.pop();
+                }
+            }
+        }
+        
+        reverse(result.begin(), result.end());
+        return result;
+    }
+};