https://leetcode.cn/problems/count-pairs-with-xor-in-a-range

Author: masx200

README.md

@@ -49,6 +49,8 @@ Step 2. Add the dependency
 
 <summary>展开查看</summary>
 
+https://leetcode.cn/problems/count-pairs-with-xor-in-a-range
+
 https://leetcode.cn/problems/path-with-minimum-effort
 
 https://leetcode.cn/problems/maximum-value-at-a-given-index-in-a-bounded-array/

count-pairs-with-xor-in-a-range/index.ts

@@ -0,0 +1,65 @@
+function countPairs(nums: number[], low: number, high: number): number {
+    return f(nums, high) - f(nums, low - 1);
+}
+
+function f(nums: number[], x: number) {
+    const HIGH_BIT = 14;
+    const root = new Trie();
+    let res = 0;
+
+    function add(num: number) {
+        let cur: Trie = root;
+        for (let k = HIGH_BIT; k >= 0; k--) {
+            const bit = (num >> k) & 1;
+
+            const next = cur.son[bit] ?? new Trie();
+            cur.son[bit] = next;
+            cur = next;
+            cur.sum++;
+        }
+    }
+
+    function get(num: number, x: number) {
+        let cur: Trie = root;
+        let sum = 0;
+        for (let k = HIGH_BIT; k >= 0; k--) {
+            const r = (num >> k) & 1;
+
+            if (((x >> k) & 1) !== 0) {
+                const next = cur.son[r];
+                if (next) {
+                    sum += next.sum;
+                }
+                const other = cur.son[r ^ 1];
+                if (!other) {
+                    return sum;
+                }
+                cur = other;
+            } else {
+                const next = cur.son[r];
+                if (!next) {
+                    return sum;
+                }
+                cur = next;
+            }
+        }
+        sum += cur.sum;
+        return sum;
+    }
+
+    for (let i = 1; i < nums.length; i++) {
+        add(nums[i - 1]);
+        res += get(nums[i], x);
+    }
+    return res;
+}
+class Trie {
+    sum: number;
+    son: (Trie | null)[];
+    // son[0] 表示左子树，son[1] 表示右子树
+    constructor() {
+        this.son = new Array<Trie | null>(2).fill(null);
+        this.sum = 0;
+    }
+}
+export default countPairs;

maximum-value-at-a-given-index-in-a-bounded-array/index.ts

@@ -7,8 +7,7 @@ function maxValue(n: number, index: number, maxSum: number): number {
         right = temp;
     }
 
-    let upper =
-        ((left + 1) * (left + 1) - 3 * (left + 1)) / 2 +
+    let upper = ((left + 1) * (left + 1) - 3 * (left + 1)) / 2 +
         left +
         1 +
         (left + 1) +
@@ -22,8 +21,7 @@ function maxValue(n: number, index: number, maxSum: number): number {
         return Math.floor((-b + Math.sqrt(b * b - 4 * a * c)) / (2 * a));
     }
 
-    upper =
-        ((2 * (right + 1) - left - 1) * left) / 2 +
+    upper = ((2 * (right + 1) - left - 1) * left) / 2 +
         (right + 1) +
         ((right + 1) * (right + 1) - 3 * (right + 1)) / 2 +
         right +