2968. Apply Operations to Maximize Frequency Score

Author: sergeyleschev

2501-3000/2968. Apply Operations to Maximize Frequency Score.swift

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+class Solution {
+
+    // Solution by Sergey Leschev
+    // 2968. Apply Operations to Maximize Frequency Score
+
+    func maxFrequencyScore(_ nums: [Int], _ k: Int) -> Int {
+        var sortedNums = nums.sorted()
+        let n = nums.count
+        var prefixSum = [Int](repeating: 0, count: n + 1)
+
+        for i in 0..<n {
+            prefixSum[i + 1] = prefixSum[i] + sortedNums[i]
+        }
+
+        var start = 0
+        var end = 1
+        var maxScore = 1
+
+        while end < n {
+            end += 1
+            let mid = (start + end) / 2
+            let target = sortedNums[mid]
+            var cost =
+                target * (mid - start) - (prefixSum[mid] - prefixSum[start])
+                + (prefixSum[end] - prefixSum[mid] - target * (end - mid))
+
+            while start < end && cost > k {
+                start += 1
+                let mid = (start + end) / 2
+                let target = sortedNums[mid]
+                cost =
+                    target * (mid - start) - (prefixSum[mid] - prefixSum[start])
+                    + (prefixSum[end] - prefixSum[mid] - target * (end - mid))
+            }
+
+            maxScore = max(maxScore, end - start)
+        }
+
+        return maxScore
+    }
+}