[LeetCode] 346. Moving Average from Data Stream 从数据流中移动平均值

Given a stream of integers and a window size, calculate the moving average of all integers in the sliding window.

For example,
MovingAverage m = new MovingAverage(3);
m.next(1) = 1
m.next(10) = (1 + 10) / 2
m.next(3) = (1 + 10 + 3) / 3
m.next(5) = (10 + 3 + 5) / 3

给一个整数流和一个窗口，计算在给定大小的窗口里的数字的平均值。

解法：队列queue，用一个queue记录进入窗口的整数。当流进窗口的整数不足时，计算所有窗口内的数字和返回，当进入窗口的整数多于窗口大小时，移除最先进入窗口的整数，新的整数进入queue，然后计算窗口内的整数和。

Java:

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public class MovingAverage {     private double previousSum = 0.0;     private int maxSize;     private Queue<Integer> currentWindow;     /** Initialize your data structure here. */     public MovingAverage(int size) {         currentWindow = new LinkedList<Integer>();         maxSize = size;     }           public double next(int val) {         if(currentWindow.size()==maxSize){             previousSum -= currentWindow.remove();         }         currentWindow.add(val);         previousSum += val;         return previousSum/currentWindow.size();     } }   /**  * Your MovingAverage object will be instantiated and called as such:  * MovingAverage obj = new MovingAverage(size);  * double param_1 = obj.next(val);  */

Java:

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public class MovingAverage {     LinkedList<Integer> queue;     int size;     double avg;        /** Initialize your data structure here. */     public MovingAverage(int size) {         this.queue = new LinkedList<Integer>();         this.size = size;     }        public double next(int val) {         if(queue.size()<this.size){             queue.offer(val);             int sum=0;             for(int i: queue){                 sum+=i;             }             avg = (double)sum/queue.size();                return avg;         }else{             int head = queue.poll();             double minus = (double)head/this.size;             queue.offer(val);             double add = (double)val/this.size;             avg = avg + add - minus;             return avg;         }     } }

Python:

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# Time:  O(1) # Space: O(w) from collections import deque   class MovingAverage(object):     def __init__(self, size):         """         Initialize your data structure here.         :type size: int         """         self.__size = size         self.__sum = 0         self.__q = deque([])       def next(self, val):         """         :type val: int         :rtype: float         """         if len(self.__q) == self.__size:             self.__sum -= self.__q.popleft()         self.__sum += val         self.__q.append(val)         return 1.0 * self.__sum / len(self.__q)     # Your MovingAverage object will be instantiated and called as such: # obj = MovingAverage(size) # param_1 = obj.next(val)

C++:

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class MovingAverage { public:     MovingAverage(int size) {         this->size = size;         sum = 0;     }           double next(int val) {         if (q.size() >= size) {             sum -= q.front(); q.pop();         }         q.push(val);         sum += val;         return sum / q.size();     }       private:     queue<int> q;     int size;     double sum; };

　　

 

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