正常写法是用栈
1 #include<iostream> 2 #include<algorithm> 3 #include<cmath> 4 #include<stack> 5 #include<cstring> 6 #include<cstdio> 7 using namespace std; 8 char c[20000000]; 9 10 stack<long long>num;//数 11 stack<char>sy;//符号 12 void mth(){//运算 13 int a,b; 14 char ch; 15 b=num.top(); 16 num.pop(); 17 a=num.top(); 18 num.pop(); 19 ch=sy.top(); 20 sy.pop(); 21 switch(ch){ 22 case '+': num.push((a+b)%10000);break; 23 case '*': num.push((a*b)%10000);break; 24 } 25 return; 26 } 27 int cmp(int ch){//优先级判断,没有严谨验证过，初步测试没有问题 28 if(sy.empty() || sy.top()=='(')return 0; 29 if(ch=='+' || ch=='-')return 1; 30 if(ch=='*' && sy.top()=='*')return 1; 31 return 0; 32 33 int main(){ 34 gets(c); 35 int len=strlen(c); 36 c[len]=')'; 37 sy.push('('); 38 int i; 39 40 if(c[0]<'0'||c[0]>'9'){ 41 num.push(0); 42 } 43 44 45 for(i=0;i<=len;i++){ 46 if(c[i]=='('){ 47 sy.push('('); 48 continue; 49 } 50 if(c[i]>='0' && c[i]<='9') 51 { 52 long long x=0; 53 while(c[i]>='0' && c[i]<='9'){ 54 x=x*10+c[i]-'0'; 55 i++; 56 } 57 i--; 58 num.push(x); 59 continue; 60 } 61 if(c[i]==')'){ 62 while(sy.top()!='(')mth(); 63 sy.pop(); 64 continue; 65 } 66 67 68 69 while(cmp(c[i]))mth(); 70 sy.push(c[i]); 71 } 72 while(!sy.empty())mth(); 73 cout<<num.top()%10000; 74 // printf("%d ",num.top()%10000); 75 return 0; 76 }