Create 2116. Check if a Parentheses String Can Be Valid (#698)

Author: Chayandas07

2116. Check if a Parentheses String Can Be Valid

@@ -0,0 +1,42 @@
+class Solution {
+public:
+    vector<bool> checkIfPrerequisite(int numCourses, vector<vector<int>>& prerequisites, vector<vector<int>>& queries) {
+        vector<vector<int>> graph(numCourses);
+        vector<int> indegree(numCourses);
+
+     
+        for(const auto& p : prerequisites) {
+            graph[p[0]].push_back(p[1]);
+            indegree[p[1]]++;
+        }
+
+        queue<int> q;
+        vector<unordered_set<int>> pre(numCourses);
+
+        for(int u = 0; u < numCourses; ++u)
+            if(!indegree[u])
+                q.push(u);
+
+        while(!q.empty()) {
+            int u = q.front(); q.pop();
+
+            for(int v : graph[u]) {
+                pre[v].insert(u);
+                pre[v].insert(pre[u].begin(), pre[u].end());
+
+                indegree[v]--;
+                if(!indegree[v])
+                    q.push(v);
+            }
+        }
+
+        
+        vector<bool> ans(queries.size());
+        for(int i = 0; i < queries.size(); ++i) {
+            int u = queries[i][0], v = queries[i][1];
+            ans[i] = pre[v].find(u) != pre[v].end();
+        }
+
+        return ans;
+    }
+};