Create cousins-in-binary-tree-ii.cpp

Author: kamyu104

C++/cousins-in-binary-tree-ii.cpp

@@ -0,0 +1,28 @@
+// Time:  O(n)
+// Space: O(w)
+
+// bfs
+class Solution {
+public:
+    TreeNode* replaceValueInTree(TreeNode* root) {
+        vector<pair<TreeNode *, int>> q = {{root, root->val}};
+        while (!empty(q)) {
+            vector<pair<TreeNode *, int>> new_q;
+            const int total = accumulate(cbegin(q), cend(q), 0, [](const auto& total, const auto& x) {
+                return total + x.first->val;
+            });
+            for (auto [node, x] : q) {
+                node->val = total - x;
+                x = (node->left ? node->left->val : 0) + (node->right ? node->right->val : 0);
+                if (node->left) {
+                    new_q.emplace_back(node->left, x);
+                }
+                if (node->right) {
+                    new_q.emplace_back(node->right, x);
+                }
+            }
+            q = move(new_q);
+        }
+        return root;
+    }
+};