【運算式求值】HDU 4192

比較水的算是運算式求值，枚舉每個變數即可............運算式求值的時候有個地方漏了i--，貢獻1wa

#define N 10005char str[N];int num[N];char op[N];int v[11];int id[11];char cmp(char a,char b){    if(a=='+'){        if(b=='+' || b=='-' || b==')')return '>';        else return '<';    }    if(a=='-'){        if(b=='+' || b=='-' || b==')')return '>';        else return '<';    }    if(a=='*'){        if(b=='(')return '<';        else return '>';    }    if(a=='('){       if(b==')')return '=';       else return '<';    }    if(a==')'){        return '>';    }}int cal(int a,int b,char c){    if(c=='+')return a+b;    if(c=='-')return a-b;    if(c=='*')return a*b;}int gao(){    int i,j;    int topnum = 0,topop = 1;    int k = 1;    op[1] = '(';    for(i=1;str[i];i++){        if(islower(str[i])){            topnum++;            num[topnum] = v[id[k++]];        } else {            char c = cmp(op[topop],str[i]);            char tag;            if(c=='<'){                topop++;                op[topop] = str[i];            } else if(c=='='){                topop--;            } else if(c=='>'){                int b = num[topnum--];                int a = num[topnum--];                tag = op[topop--];                int res = cal(a,b,tag);                topnum++;                num[topnum] = res;                i--;//fuck            }        }    }    return num[topnum];}int main(){    int n;    while(scanf("%d",&n) && n){        int i,j;        for(i=1;i<=n;i++){            scanf("%d",&v[i]);            id[i] = i;        }        int ans;        scanf("%d",&ans);        scanf("%s",str+1);        int len = strlen(str+1);        str[0] = '(',str[len+1] = ')',str[len+2] = '\0';        bool ok =0;        do{            int tmp = gao();            if(tmp==ans){                ok = 1;                break;            }        }while(next_permutation(id+1,id+1+n));        if(ok)puts("YES");        else puts("NO");    }    return 0;}