init

23/05/1373.c

@@ -0,0 +1,57 @@
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+
+const int INF = 0x3f3f3f3f;
+
+
+struct TreeNode {
+    int val;
+    struct TreeNode *left;
+    struct TreeNode *right;
+};
+
+typedef struct SubTree {
+    bool isBST;
+    int minValue;
+    int maxValue;
+    int sumValue;
+} SubTree;
+
+SubTree *createSubTree(bool isBST, int minValue,int maxValue, int sumValue) {
+    SubTree *obj = (SubTree *)malloc(sizeof(SubTree));
+    obj->isBST = isBST;
+    obj->minValue = minValue;
+    obj->maxValue = maxValue;
+    obj->sumValue = sumValue;
+    return obj;
+}
+
+SubTree* dfs(struct TreeNode* root, int *res) {
+    if (root == NULL) {
+        return createSubTree(true, INF, -INF, 0);
+    }
+    SubTree *left = dfs(root->left, res);
+    SubTree *right = dfs(root->right, res);
+    SubTree *ret = NULL;
+
+    if (left->isBST && right->isBST &&
+          root->val > left->maxValue &&
+          root->val < right->minValue) {
+        int sum = root->val + left->sumValue + right->sumValue;
+        *res = MAX(*res, sum);
+        ret = createSubTree(true, MIN(left->minValue, root->val), \
+                            MAX(root->val, right->maxValue), sum);
+    } else {
+        ret = createSubTree(false, 0, 0, 0);
+    }
+    free(left);
+    free(right);
+    return ret;
+}
+
+int maxSumBST(struct TreeNode* root){
+    int res = 0;
+    SubTree *obj = dfs(root, &res);
+    free(obj);
+    return res;
+}