1707

Author: lzl124631x

leetcode/1707. Maximum XOR With an Element From Array/README.md

@@ -51,39 +51,34 @@ struct TrieNode {
     int minVal = INT_MAX;
 };
 class Solution {
+    void add(TrieNode *node, int n) {
+        for (int i = 31; i >= 0; --i) {
+            int b = n >> i & 1;
+            if (node->next[b] == NULL) node->next[b] = new TrieNode();
+            node = node->next[b];
+            node->minVal = min(node->minVal, n);
+        }
+    }
+    int maxXor(TrieNode *node, int x, int m) {
+        int ans = 0;
+        for (int i = 31; i >= 0; --i) {
+            int b = x >> i & 1;
+            if (node->next[1 - b] && node->next[1 - b]->minVal <= m) {
+                node = node->next[1 - b];
+                ans |= 1 << i;
+            } else if (node->next[b] && node->next[b]->minVal <= m) node = node->next[b];
+            else return -1;
+        }
+        return ans;
+    }
 public:
     vector<int> maximizeXor(vector<int>& A, vector<vector<int>>& Q) {
         TrieNode root;
-        for (int n : A) {
-            auto node = &root;
-            node->minVal = min(node->minVal, n);
-            for (int i = 31; i >= 0; --i) {
-                int b = (n >> i) & 1;
-                if (!node->next[b]) node->next[b] = new TrieNode();
-                node = node->next[b];
-                node->minVal = min(node->minVal, n);
-            }
-        }
         vector<int> ans;
+        for (int n : A) add(&root, n);
         for (auto &q : Q) {
-            int x = q[0], m = q[1], val = 0;
-            auto node = &root;
-            if (node->minVal > m) {
-                ans.push_back(-1);
-                continue;
-            }
-            for (int i = 31; i >= 0; --i) {
-                int b = (x >> i) & 1, r = 1 ^ b;
-                if (node->next[r] && node->next[r]->minVal <= m) {
-                    node = node->next[r];
-                    val |= (1 << i);
-                } else if (node->next[b]->minVal <= m) node = node->next[b];
-                else {
-                    val = -1;
-                    break;
-                }
-            }
-            ans.push_back(val);
+            int x = q[0], m = q[1];
+            ans.push_back(maxXor(&root, x, m));
         }
         return ans;
     }