Array.length is even

* * *  * * *
    ^
    (Array.length-1)/2

* * *  * * *
       ^
       Array.length/2

当Array.length is even, -1 对中值index有影响


Array.length is odd

* *  *  * *
     ^
     (Array.length-1)/2 == Array.length/2

当Array.length is odd, -1 对中值index无影响

example:

1: reverse Array
for(int i=0;i<array.length/2;++i){
  int tmp=array[array.length-1-i];
  array[array.length-1-i]=array[i];
  array[i]=tmp;
}