输入序列为 ABC ,可以变为 CBA 时,经过的栈操作为 。 push,pop,push,pop,push,pop push,push,push,pop, pop, pop push,push,pop, pop,push,pop push,pop,push,push,pop, pop
push,pop,push,pop,push,pop
push,push,push,pop, pop, pop
push,push,pop, pop,push,pop
push,pop,push,push,pop, pop