BFS-1 Completed

course_scheudle_207.cpp

@@ -0,0 +1,49 @@
+//course schedule
+class Solution {
+public:
+    bool canFinish(int numCourses, vector<vector<int>>& prerequisites) {
+        queue<int> q;
+        int count=0;
+        unordered_map<int, vector<int>> map;
+        vector<int> inorder(numCourses, 0);
+
+        for(int i=0;i<prerequisites.size();i++)
+        {
+            inorder[prerequisites[i][0]]++;
+            map[prerequisites[i][1]].push_back(prerequisites[i][0]);
+        }
+        for(int i=0;i<inorder.size();i++)
+        {
+            if(inorder[i]==0)
+            {
+                  q.push(i);
+                  count++;
+            }
+
+        }
+        if(q.empty())
+            return false;
+        while(!q.empty())
+        {
+            int node=q.front();
+            q.pop();
+            for(auto [key,val]: map)
+            {
+                if(key==node)
+                {
+                    for(auto x: val)
+                    {
+                        inorder[x]--;
+                        if(inorder[x]==0)
+                        {
+                             q.push(x);
+                             count++;
+                        }
+
+                    }
+                }
+            }
+        }
+return count==numCourses;
+    }
+};

levelOrderTraversal_102.cpp

@@ -0,0 +1,42 @@
+**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+//O(n)
+//O(n)
+class Solution {
+public:
+    vector<vector<int>> levelOrder(TreeNode* root) {
+        queue<TreeNode*> q;
+        vector<int> path;
+        vector<vector<int>> res;
+        if(root==nullptr)
+            return {};
+        q.push(root);
+        while(!q.empty())
+        {
+            int size=q.size();
+
+            for(int i=0;i<size;i++)
+            {
+                TreeNode* node=q.front(); q.pop();
+                path.push_back(node->val);
+                if(node->left!=nullptr)
+                    q.push(node->left);
+                if(node->right!=nullptr)
+                    q.push(node->right);
+            }
+            res.push_back(path);
+            path.clear();
+        }
+        return res;
+    }
+};
+