多重输入判断-流程图代码

```flow
st=>start: 开始
e=>end: 结束
cond0=>condition: 输入==0？
cond1=>condition: 输入==1？
cond2=>condition: 输入==2？
cond3=>condition: 输入==3？
op0=>operation: 执行分配
op1=>operation: 执行回收
op2=>operation: 执行拼接
op3=>operation: 退出程序
op=>operation: 检测输入
st->op->cond0->e
cond0(no)->cond1
cond1(no)->cond1
cond2(no)->cond1
cond0(no)->cond1
cond1(no)->cond2
cond2(no)->cond3
cond3(no)->op
cond3(no)->op

cond3(yes)->op3
op3->e
cond0(yes)->op0
cond1(yes)->op1
cond2(yes)->op2
op0(right)->op
op1(right)->op
op2(right)->op