add 990

Author: luliyucoordinate

README.md

@@ -321,4 +321,5 @@ LeetCode
 |0986|[Interval List Intersections](https://leetcode.com/problems/interval-list-intersections/) | c | [c++](./src/0986-Interval-List-Intersections/0986.cpp) |[python](./src/0986-Interval-List-Intersections/0986.py)|||Medium|
 |0987|[Vertical Order Traversal of a Binary Tree](https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree/) | c | [c++](./src/0987-Vertical-Order-Traversal-of-a-Binary-Tree/0987.cpp) |[python](./src/0987-Vertical-Order-Traversal-of-a-Binary-Tree/0987.py)|||Medium|
 |0988|[Smallest String Starting From Leaf](https://leetcode.com/problems/smallest-string-starting-from-leaf/) | c | [c++](./src/0988-Smallest-String-Starting-From-Leaf/0988.cpp) |[python](./src/0988-Smallest-String-Starting-From-Leaf/0988.py)|||Medium|
-|0989|[Add to Array-Form of Integer](https://leetcode.com/problems/add-to-array-form-of-integer/) | c | [c++](./src/0989-Add-to-Array-Form-of-Integer/0989.cpp) |[python](./src/0989-Add-to-Array-Form-of-Integer/0989.py)|||Easy|
+|0989|[Add to Array-Form of Integer](https://leetcode.com/problems/add-to-array-form-of-integer/) | c | [c++](./src/0989-Add-to-Array-Form-of-Integer/0989.cpp) |[python](./src/0989-Add-to-Array-Form-of-Integer/0989.py)|||Easy|
+|0990|[Satisfiability of Equality Equations](https://leetcode.com/problems/satisfiability-of-equality-equations/) | c | [c++](./src/0990-Satisfiability-of-Equality-Equations/0990.cpp) |[python](./src/0990-Satisfiability-of-Equality-Equations/0990.py)|||Easy|

src/0990-Satisfiability-of-Equality-Equations/0990.cpp

@@ -0,0 +1,29 @@
+static int x = [](){std::ios::sync_with_stdio(false);cin.tie(0);return 0;}();
+class Solution 
+{
+public:
+    bool equationsPossible(vector<string>& equations) 
+    {
+        for (int i = 0; i < 26; ++i) _parents[i] = i;
+        for (string& e : equations)
+        {
+            if (e[1] == '=')
+                _parents[_find(e[0] - 'a')] = _find(e[3] - 'a');
+        }
+            
+        for (string& e : equations)
+        {
+            if (e[1] == '!' && _find(e[0] - 'a') == _find(e[3] - 'a'))
+                return false;
+        }
+        return true;       
+    }
+private:
+    int _parents[26];
+
+    int _find(int x) 
+    {
+        if (x != _parents[x]) _parents[x] = _find(_parents[x]);
+        return _parents[x];
+    }
+};

src/0990-Satisfiability-of-Equality-Equations/0990.py

@@ -0,0 +1,18 @@
+class Solution:
+    def equationsPossible(self, equations: 'List[str]') -> 'bool':
+        tmp = {chr(i): chr(i) for i in range(97, 125)}
+        
+        def find(x):
+            if x != tmp[x]:
+                tmp[x]= find(tmp[x])
+            return tmp[x]
+        
+        for it in equations:
+            if it[1] == '=':
+                tmp[find(it[0])] = find(it[-1])
+                
+        for it in equations:
+            if it[1] == '!':
+                if find(it[0]) == find(it[-1]):
+                    return False
+        return True