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We sampled integers between 0 and 255, and stored the results in an array count:  count[k] is the number of integers we sampled equal to k.

Return the minimum, maximum, mean, median, and mode of the sample respectively, as an array of floating point numbers.  The mode is guaranteed to be unique.

(Recall that the median of a sample is:

• The middle element, if the elements of the sample were sorted and the number of elements is odd;
• The average of the middle two elements, if the elements of the sample were sorted and the number of elements is even.)

Example 1:

Input: count = [0,1,3,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]Output: [1.00000,3.00000,2.37500,2.50000,3.00000]

Example 2:

Input: count = [0,4,3,2,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]Output: [1.00000,4.00000,2.18182,2.00000,1.00000]

Constraints:

1. count.length == 256
2. 1 <= sum(count) <= 10^9
3. The mode of the sample that count represents is unique.
4. Answers within 10^-5 of the true value will be accepted as correct.

---

我们对 0 到 255 之间的整数进行采样，并将结果存储在数组 count 中：count[k] 意味着采样的整数为 k。

我们以 浮点数 数组的形式，分别返回样本的最小值、最大值、平均值、中位数和众数。其中，众数是保证唯一的。

我们先来回顾一下中位数的知识：

• 如果样本中的元素有序，并且元素数量为奇数时，中位数为最中间的那个元素；
• 如果样本中的元素有序，并且元素数量为偶数时，中位数为中间的两个元素的平均值。

示例 1：

输入：count = [0,1,3,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]输出：[1.00000,3.00000,2.37500,2.50000,3.00000]

示例 2：

输入：count = [0,4,3,2,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]输出：[1.00000,4.00000,2.18182,2.00000,1.00000]

提示：

1. count.length == 256
2. 1 <= sum(count) <= 10^9
3. 计数表示的众数是唯一的
4. 答案与真实值误差在 10^-5 以内就会被视为正确答案

---

20ms

1 class Solution { 2     func sampleStats(_ count: [Int]) -> [Double] { 3         guard count.count == 256 else {  4             assert(1 == 0, "Input error")  5         } 6         var result = [Double]() 7         var left = 0 8         var right = 255 9         while left <= 255 && count[left] == 0 {10             left += 111         }12         13         while right > left && count[right] == 0 {14             right -= 115         }16         17         result.append(Double(left))18         result.append(Double(right))19         20         var counter = 021         var sum = 022         var mode = 023         var modeCounter = 024         for i in count.indices {25             if count[i] > modeCounter {26                 modeCounter = count[i]27                 mode = i28             }29             counter += count[i]30             sum += i * count[i]31         }32         result.append(Double(sum) / Double(counter))33         34         var start = counter % 2 != 0 ? counter / 2 + 1 : counter / 235         for i in 0..
      
        0 {37                 // print(start)38                 // print(i)39                 start -= count[i]40                 continue41             }42             43             if counter % 2 != 0 {44                 result.append(Double(i))45                 break46             } else {47                 if start - count[i] == 0 {48                     var curr = i + 149                     50                     while curr <= 255 && count[curr] == 0 {51                         curr += 152                     } 53                     result.append(Double(curr + i) / Double(2))54                     break55                 } else if start - count[i] < 0 {56                     result.append(Double(i))57                     break58                 } 59             }60         }61 62         result.append(Double(mode))63         return result64     }65 }
      

---

Runtime: 24 ms

Memory Usage: 21.2 MB

1 class Solution { 2     func sampleStats(_ count: [Int]) -> [Double] { 3         var L:Int = 0 4         var R:Int = 255 5         while(L < 256 && count[L] == 0) 6         { 7             L += 1 8         } 9         while(L >= 0 && count[R] == 0)10         {11             R -= 112         }13         let n:Int = count.reduce(0,+)14         var sum:Double = 015         for i in 0...25516         {17             sum += Double(i * count[i])18         }19         let ave:Double = sum / Double(n)20         var cur:Int = 021         var mid:Double = 022         if (n & 1) != 023         {24             cur = 025             for i in 0...25526             {27                 cur += count[i]28                 if cur >= (n + 1) / 229                 {30                     mid = Double(i)31                     break32                 }33             }34         }35         else36         {37             let x:Int = n / 238             let y:Int = x + 139             cur = 040             for i in 0...25541             {42                 cur += count[i]43                 if cur >= x44                 {45                     mid += Double(i)46                     break47                 }48             }49             cur = 050             for i in 0...25551             {52                 cur += count[i]53                 if cur >= y54                 {55                     mid += Double(i)56                     break57                 }58             }59             mid /= 260         }61         let max_freq:Int = count.max() ?? Int.max62         var mode:Double = -1.063         for i in 0...25564         {65             if count[i] == max_freq66             {67                 mode = Double(i)68             }69         }70         return [Double(L), Double(R), ave, mid, mode]71     }72 }

---

36ms

 

1 class Solution { 2   func sampleStats(_ count: [Int]) -> [Double] { 3     var minN = Int.max 4     var maxN = Int.min 5     var median: Double = 0 6     var mode = 0 7     var modeVal = 0 8     var countOfNum = 0 9     var sumVal = 010     for pair in count.enumerated() {11       if pair.element != 0 {12         minN = min(minN, pair.offset)13         maxN = max(maxN, pair.offset)14         if pair.element > mode {15           mode = pair.element16           modeVal = pair.offset17         }18         sumVal += pair.offset * pair.element19         countOfNum += pair.element20       }21     }22     23     if countOfNum % 2 == 1 {24       median = Double(valueBy(index: countOfNum/2, a: count))25     } else {26       median = Double(valueBy(index: countOfNum/2, a: count) + valueBy(index: countOfNum/2 - 1, a: count))/227     }28     29     return [Double(minN), Double(maxN), Double(sumVal)/Double(countOfNum), median, Double(modeVal)]30   }31   32   func valueBy(index: Int, a: [Int]) -> Int {33     var curentIndex = 034     for pair in a.enumerated() {35       curentIndex += pair.element36       if curentIndex > index {37         return pair.offset38       }39     }40     fatalError()41   }42 }