算法导论chapter6.2-5
max_heapify(a,n,i) largest=i; temp=-1; while(lagest<=n) then l=2*largest; r=2*largest+1; if(l<=n and a[l]>a[largest]) then largest=l; if(r<=n and a[r]>a[largest]) then largest=r; if(largest!=temp) then a[laegest]<->a[temp]; else break;