leetcode实践“数据流移动平均线”的数据类型转换问题

Question

When I was running the code for the leetcode question ""Moving Average from Data Stream"". I got a partly different output with the expected: Here is my code:

class MovingAverage {
    
    int front = 0, rear = 0; Double sum = 0.00000;
    int[] data;

    
    public MovingAverage(int size) {
        
        data = new int[size];
        Arrays.fill(data, 0);
        
        
        
    }
    
    public double next(int val) {
        
        if(data.length == 1){
            data[rear] = val;
            return val;
        }else{
             if(rear < data.length){
             data[rear] = val;
             sum += data[rear];
             rear++;         
             return sum/rear;
                 
         }else{
             sum -= data[front];
             rear = (rear+1) % data.length - 1;
             front = (front+1) % data.length ;
             data[rear] = val;
             sum += data[rear];
             rear++;
             return sum/data.length;
         }
         
        }
        

         
    }
}

The requirement for code is:

When I run the tast cases of the example provided, everything is ok. But when I run this edge case, thing is different: ["MovingAverage","next","next","next","next","next","next","next","next","next","next"] [[5],[12009],[1965],[-940],[-8516],[-16446],[7870],[25545],[-21028],[18430],[-23464]]

Anyone can help me pls? Is my code wrong or I didn't process the data conversion well?

Answer 1

This logical check is incorrect:

if (rear < data.length)

In the corresponding else block, when rear = data.length , you set rear = (rear+1) % data.length - 1 , so rear < data.length becomes true in the next iteration, and you go back to the if block again. However, the logic to dequeue and update values is in the else block (which is where you should end up once data is filled completely). This is why you're getting an incorrect answer; if (rear < data.length) isn't correct.

Replacing that condition with something like if (numberOfElementsTillNow < data.length) should fix this issue.

Answer 2

I revised my code, and the answer accepted:

class MovingAverage {

int front = 0, rear = 0; int sum = 0;
int[] data;


public MovingAverage(int size) {
    
    data = new int[size];
    Arrays.fill(data, 0);
    
    
    
}

public double next(int val) {
    
    if(data.length == 1){
        data[rear] = val;
        return (double)val;
    }else{
         if(rear < data.length){
         data[rear] = val;
         sum += (int)data[rear];
         rear++;         
         return sum * 1.0/rear;
             
     }else{
         sum -= (int)data[front % data.length];
         data[rear % data.length] = val;
         sum += (int)data[rear % data.length];
         rear++;
         front++;
         return sum * 1.0/data.length;
     }
     
    }
    

     
}

}

This issue can be closed.