对于一个栈，已知元素的进栈序列，判断一个由栈中所有元素组成的排列是否是可能的出栈序列。



比如，进栈序列为1 2 3 4，则可能的出栈序列有4 3 2 1，1 4 3 2等。而1 4 2 3就不是。-For a stack, a known sequence of elements into the stack to determine a stack with all the elements of the composition of whether it is possible to sequence the stack. For example, the stack into the sequence 1 2 3 4, you may stack the sequence of the 4 3 2 1,1 4 3 2 and so on. And 1 4 2 3 is not.