Create basic_calculator.go

Author: sangam14

golang/basic_calculator/basic_calculator.go

@@ -0,0 +1,32 @@
+package basic_calculator
+
+func calculate(s string) int {
+	ret := 0
+	stack := []int{}
+	sign := 1
+	for i := 0; i < len(s); i++ {
+		if s[i] >= '0' && s[i] <= '9' {
+			num := 0
+			for ; i < len(s) && s[i] >= '0' && s[i] <= '9'; i++ {
+				num = 10*num + int(s[i]-'0')
+			}
+			ret += sign * num
+			i--
+		} else if s[i] == '+' {
+			sign = 1
+		} else if s[i] == '-' {
+			sign = -1
+		} else if s[i] == '(' {
+			stack = append(stack, ret, sign)
+			ret = 0
+			sign = 1
+		} else if s[i] == ')' {
+			signTmp := stack[len(stack)-1]
+			retTmp := stack[len(stack)-2]
+			stack = stack[:len(stack)-2]
+			ret = signTmp*ret + retTmp
+			sign = 1
+		}
+	}
+	return ret
+}