class?Solution?{
public:
????int?calculate(string?s)?{
????????static?const?int?STATE_BEGIN?=?0;
????????static?const?int?NUMBER_STATE?=?1;
????????static?const?int?OPERATION_STATE?=?2;
????????std::stack<int>?number_stack;
????????std::stack<char>?operation_stack;
????????long?number?=?0;
????????int?STATE?=?STATE_BEGIN;
????????int?compuate_flag?=?0;
????????for?(int?i?=?0;?i?<?s.length();?i++){
????????????if?(s[i]?==?'?'){
????????????????continue;
????????????}
????????????switch(STATE){
????????????case?STATE_BEGIN:
????????????????if?(s[i]?>=?'0'?&&?s[i]?<=?'9'){
????????????????????STATE?=?NUMBER_STATE;
????????????????}
????????????????else{
????????????????????STATE?=?OPERATION_STATE;
????????????????}
????????????????i--;
????????????????break;
????????????case?NUMBER_STATE:
????????????????if?(s[i]?>=?'0'?&&?s[i]?<=?'9'){
????????????????????number?=?number?*?10?+?s[i]?-?'0';
????????????????}
????????????????else{
????????????????????number_stack.push(number);
????????????????????if?(compuate_flag?==?1){
????????????????????????compute(number_stack,?operation_stack);
????????????????????}
????????????????????number?=?0;
????????????????????i--;
????????????????????STATE?=?OPERATION_STATE;
????????????????}
????????????????break;
????????????case?OPERATION_STATE:
????????????????if?(s[i]?==?'+'?||?s[i]?==?'-'){
????????????????????operation_stack.push(s[i]);
????????????????????compuate_flag?=?1;
????????????????}
????????????????else?if?(s[i]?==?'('){
????????????????????STATE?=?NUMBER_STATE;
????????????????????compuate_flag?=?0;
????????????????}
????????????????else?if?(s[i]?>=?'0'?&&?s[i]?<=?'9'){
????????????????????STATE?=?NUMBER_STATE;???????????????????
????????????????????i--;
????????????????}
????????????????else?if?(s[i]?==?')'){
????????????????????compute(number_stack,?operation_stack);
????????????????}
????????????????break;
????????????}
????????}
????????if?(number?!=?0){
????????????number_stack.push(number);
????????????compute(number_stack,?operation_stack);
????????}
????????if?(number?==?0?&&?number_stack.empty()){
????????????return?0;
????????}
????????return?number_stack.top();
????}
???void?compute(std::stack<int>?&number_stack,
?????????????????std::stack<char>?&operation_stack){
????????if?(number_stack.size()?<?2){
????????????return;
????????}
????????int?num2?=?number_stack.top();
????????number_stack.pop();
????????int?num1?=?number_stack.top();
????????number_stack.pop();
????????if?(operation_stack.top()?==?'+'){
????????????number_stack.push(num1?+?num2);
????????}
????????else?if(operation_stack.top()?==?'-'){
????????????number_stack.push(num1?-?num2);
????????}
????????operation_stack.pop();
????}
};
