Basic Calculator II

// 227. Basic Calculator II // // https://leetcode.com/problems/basic-calculator-ii/ // strings package is used for replacing spaces to nothing. // unicode package is used for checking the rune is digit or not. import ( "strings" "unicode" ) // calculate function calculates the given string expression. // Only "+", "-", "*", "/" operators are allowed. // As many spaces as possible between operands and operators. // Such a simple calculating does not require the stack operation. func calculate(s string) int { num, temp, res, lastOperator := 0, 0, 0, '+' strings.Replace(s, " ", "", -1) for i, char := range s { if unicode.IsDigit(char) { num = num*10 + (int(char - '0')) } if i == len(s)-1 || char == '+' || char == '-' || char == '*' || char == '/' { switch lastOperator { case '+': res += temp temp = num case '-': res += temp temp = -num case '*': temp *= num case '/': temp /= num } num = 0 lastOperator = char } } res += temp return res }