去括号-题解(C++代码)

#include <iostream>
#include <cstring>
using namespace std;
void qukuohao(int left,int right,char a[])
{
    int inside,outside;//括号内等级和括号外等级
    int zuo,you;//左括号等级和右括号等级
    //对于括号外等级，只要判断括号外一格的符号
    if(left==0||a[left-1]=='('||a[left-1]=='+'||a[left-1]==-1)zuo=1;
    else if(a[left-1]=='-')zuo=2;//-在括号前面等级介于'+'和'*'之间
    else if(a[left-1]=='*')zuo=3;
    else if(a[left-1]=='/')zuo=4;//除同理
    else if(a[left-1]=='^')zuo=5;
    if(right==strlen(a)-1||a[right+1]==')'||a[right+1]=='+'||a[right+1]=='-'||a[right+1]==-1)you=1;
    else if(a[right+1]=='*'||a[right+1]=='/')you=3;
    else if(a[right+1]=='^')you=5;
    outside=zuo>you?zuo:you;
    //对于括号内等级，要么括号内一格是括号，要么括号内两格是符号
    if(a[left+1]=='('||a[left+2]=='+'||a[left+2]=='-'||a[left+2]==-1||a[left+2]==')')zuo=1;
    else if(a[left+2]=='*'||a[left+2]=='/')zuo=3;
    else if(a[left+2]=='^')zuo=5;
    if(a[right-1]==')'||a[right-2]=='+'||a[right-2]=='-'||a[right-2]==-1||a[right-2]=='(')you=1;
    else if(a[right-2]=='*'||a[right-2]=='/')you=3;
    else if(a[right-2]=='^')you=5;
    inside=zuo>you?zuo:you;
    if(inside>=outside)//若括号内等级大于等于括号外等级去括号
    {
        a[left]=-1;
        a[right]=-1;
    }
}
int main()
{
    char a[21];
    while(1)
    {
        cin.getline(a,21);
        if(a[0]=='\0'||a[0]=='#')break;
        int len=strlen(a);
        int left=0,right=0;
        while(left<len&&len)
        {
            //下一左括号
            while(left<len)
            {
                if(a[left]=='(')break;
                left++;
            }
            //下一右括号
            right=left+1;
            int temp=0;//表示中间括号数量
            while(right<len)
            {
                //跳过中间括号
                if(a[right]==')'&&temp==0)break;
                else if(a[right]==')'&&temp!=0)temp--;
                else if(a[right]=='(')temp++;
                right++;
            }
            if(left<len)qukuohao(left,right,a);
            left++;
        }
        //打印
        for(int i=0;i<len;i++)
            if(a[i]!=-1)cout<<a[i];
        cout<<endl;
    }
    return 0;
}