Create 2003.cpp

LeetCode/2003.cpp

@@ -0,0 +1,50 @@
+
+class Solution {
+public:
+    void updateSubtree(vector<bool>& subtree, const vector<vector<int>>& childs, const vector<int>& nums, int rootIndex, int skipIndex) {
+        //printf("updateSubtree: %d\n", rootIndex);
+        subtree[nums[rootIndex]] = true;
+        for (auto& childIndex : childs[rootIndex]) {
+            if (skipIndex != -1 && skipIndex == childIndex) {
+                //printf("skip %d\n", skipIndex);
+                continue;
+            }
+            updateSubtree(subtree, childs, nums, childIndex, skipIndex);
+        }
+    }
+
+    vector<int> smallestMissingValueSubtree(vector<int>& parents, vector<int>& nums) {
+        const int n = parents.size();
+        vector<int> result(n, 1);
+        auto iter = find(nums.begin(), nums.end(), 1);
+        if (iter == nums.end()) {
+            return result;
+        }
+
+        vector<vector<int>> childs(n);
+        for (int i = 0; i < n; i++) {
+            if (parents[i] == -1) continue;
+            childs[parents[i]].push_back(i);
+        }
+
+        vector<bool> subtreeValues(100002);
+        
+        const int beginIndex = iter - nums.begin();
+        int currentIndex = beginIndex;
+        int skipIndex = -1;
+        int nextGap = 1;
+        while (currentIndex != -1) {
+            updateSubtree(subtreeValues, childs, nums, currentIndex, skipIndex);
+            for (; nextGap < 100002; nextGap++) {
+                if (!subtreeValues[nextGap]) {
+                    result[currentIndex] = nextGap;
+                    break;
+                }
+            }
+            skipIndex = currentIndex;
+            currentIndex = parents[currentIndex];
+        }
+
+        return result;
+    }
+};