https://leetcode.cn/problems/maximum-value-at-a-given-index-in-a-bounded-array/

Author: masx200

README.md

@@ -51,6 +51,8 @@ Step 2. Add the dependency
 
 https://leetcode.cn/problems/path-with-minimum-effort
 
+https://leetcode.cn/problems/maximum-value-at-a-given-index-in-a-bounded-array/
+
 https://leetcode.cn/problems/last-day-where-you-can-still-cross/
 
 https://leetcode.cn/problems/bricks-falling-when-hit/

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

@@ -0,0 +1,42 @@
+function maxValue(n: number, index: number, maxSum: number): number {
+    let left = index;
+    let right = n - index - 1;
+    if (left > right) {
+        const temp = left;
+        left = right;
+        right = temp;
+    }
+
+    let upper =
+        ((left + 1) * (left + 1) - 3 * (left + 1)) / 2 +
+        left +
+        1 +
+        (left + 1) +
+        ((left + 1) * (left + 1) - 3 * (left + 1)) / 2 +
+        right +
+        1;
+    if (upper >= maxSum) {
+        const a = 1;
+        const b = -2;
+        const c = left + right + 2 - maxSum;
+        return Math.floor((-b + Math.sqrt(b * b - 4 * a * c)) / (2 * a));
+    }
+
+    upper =
+        ((2 * (right + 1) - left - 1) * left) / 2 +
+        (right + 1) +
+        ((right + 1) * (right + 1) - 3 * (right + 1)) / 2 +
+        right +
+        1;
+    if (upper >= maxSum) {
+        const a = 1.0 / 2;
+        const b = left + 1 - 3.0 / 2;
+        const c = right + 1 + ((-left - 1) * left) / 2 - maxSum;
+        return Math.floor((-b + Math.sqrt(b * b - 4 * a * c)) / (2 * a));
+    } else {
+        const a = left + right + 1;
+        const b = (-left * left - left - right * right - right) / 2 - maxSum;
+        return Math.floor(-b / a);
+    }
+}
+export default maxValue;