leetcode 227

readme.md

leetcode 227

Created with <3 with dartpad.dev.

main.dart

void main() {

  Solution solution = Solution();
  print(solution.calculate("14-3/2"));
}

class Solution {
    int calculate(String s) {
        List<String> chs = s.split('');
        
        int result = 0;
        List<int> stack = [];
        String prevChar = 'a';
        String operator = 'a';
        int number = 0;
        
        for(int i = 0 ; i < chs.length ; i++){
          if(chs[i] == ' ') {
              continue;
          }
          
          if(chs[i].codeUnitAt(0) >= '0'.codeUnitAt(0) && chs[i].codeUnitAt(0) <= '9'.codeUnitAt(0)){
            
            if(prevChar.codeUnitAt(0) >= '0'.codeUnitAt(0) && prevChar.codeUnitAt(0) <= '9'.codeUnitAt(0)){
               number= (number * 10) + int.parse(chs[i]);
            }
            else{
              number = int.parse(chs[i]);
            }    
          }
          
          else {
            
            if(operator == 'a'){
              stack.add(number);

            }

            if(operator == '+'){
              
                stack.add(number);
            }
            else if(operator == '-'){
                stack.add(-number);
            }
            else if(operator == '*'){
              stack.add(number * stack.removeLast());
            }
            else if(operator == '/'){
                stack.add(stack.removeLast() ~/ number);
            }  
            
            
        
            operator = chs[i];
            number = 0; 
          }
         
          prevChar = chs[i];
        }
        

            
        if(operator == 'a'){
            stack.add(number);
        }
        if(operator == '+'){

            stack.add(number);
        }
        else if(operator == '-'){
            stack.add(-number);
        }
        else if(operator == '*'){
          stack.add(number * stack.removeLast());
        }
        else if(operator == '/'){
            
            stack.add(stack.removeLast() ~/ number);
        }  
      
      print(stack);
      
      for(int n in stack){
        result = result + n;
      }
      return result;
    }
}