平行比赛。如何返回数组最大值的位置

Question

我需要编写一个算法来使用并行锦标赛找到最大值的位置。我有这段代码来找到最大值：

  

//共享内存变量n：值M [0..n-1]：值为

的数组      

//并行程序

torneoMaxParalelo(M,n)
int incr=1;
int grande, temp0, temp1; 
while (incr < n)

    temp0 ← M[pid];
    if (pid + incr < n)
       temp1 ← M[pid + incr];
    else
       temp1 ← -infinite;
    grande ← max(temp0, temp1);
    M[pid] ← grande;
    incr = 2 * incr;

算法应该花费O（log n）时间。非常感谢你。

Answer 1

这是伪代码。

 parTournMaxIndex(M, idx, n)  
 int incr;  
 Write -infinite (some very
 small value) into M[n].  
 Write pid into idx[pid] and write n into idx[pid+n].
 incr = 1;  
 int idx0, idx1, idxBig;  
 Key key0, key1;
 while (incr < n) 
    Read idx[pid] into idx0 and read idx[pid+incr] into idx1.  
    Read M[idx0] into key0 and read M[idx1] into key1.  
    if (key1 > key0) idxBig = idx1; 
    else idxBig = idx0;  
    Write idxBig into idx[pid].  
    incr = 2 * incr;