Update satisfiability-of-equality-equations.cpp

Author: kamyu104

C++/satisfiability-of-equality-equations.cpp

@@ -2,6 +2,60 @@
 // Space: O(1)
 
 class Solution {
+public:
+    bool equationsPossible(vector<string>& equations) {
+        UnionFind union_find(26);
+        for (const auto& eqn : equations) {
+            int x = eqn[0] - 'a';
+            int y = eqn[3] - 'a';
+            if (eqn[1] == '=') {
+                union_find.union_set(x, y);
+            }
+        }
+        for (const auto& eqn : equations) {
+            int x = eqn[0] - 'a';
+            int y = eqn[3] - 'a';
+            if (eqn[1] == '!') {
+                if (union_find.find_set(x) == union_find.find_set(y)) {
+                    return false;
+                }
+            }
+        }
+        return true; 
+    }
+    
+
+private:
+    class UnionFind {
+    public:
+        UnionFind(const int n) : set_(n) {
+            iota(set_.begin(), set_.end(), 0);
+        }
+
+        int find_set(const int x) {
+           if (set_[x] != x) {
+               set_[x] = find_set(set_[x]);  // Path compression.
+           }
+           return set_[x];
+        }
+
+        bool union_set(const int x, const int y) {
+            int x_root = find_set(x), y_root = find_set(y);
+            if (x_root == y_root) {
+                return false;
+            }
+            set_[min(x_root, y_root)] = max(x_root, y_root);
+            return true;
+        }
+
+    private:
+        vector<int> set_;
+    };
+};
+
+// Time:  O(n)
+// Space: O(1)
+class Solution2 {
 public:
     bool equationsPossible(vector<string>& equations) {
         vector<vector<int>> graph(26);