Merge pull request halfrost#143 from novahe/fix/150

halfrost · web-flow · commit 3dac8b9e82a3 · 2021-06-01T13:08:48.000+08:00
clean up redundant code
diff --git a/leetcode/0150.Evaluate-Reverse-Polish-Notation/150. Evaluate Reverse Polish Notation.go b/leetcode/0150.Evaluate-Reverse-Polish-Notation/150. Evaluate Reverse Polish Notation.go
@@ -5,46 +5,23 @@ import (
 )
 
 func evalRPN(tokens []string) int {
-	if len(tokens) == 1 {
-		i, _ := strconv.Atoi(tokens[0])
-		return i
-	}
-	stack, top := []int{}, 0
-	for _, v := range tokens {
-		switch v {
-		case "+":
-			{
-				sum := stack[top-2] + stack[top-1]
-				stack = stack[:top-2]
-				stack = append(stack, sum)
-				top--
-			}
-		case "-":
-			{
-				sub := stack[top-2] - stack[top-1]
-				stack = stack[:top-2]
-				stack = append(stack, sub)
-				top--
-			}
-		case "*":
-			{
-				mul := stack[top-2] * stack[top-1]
-				stack = stack[:top-2]
-				stack = append(stack, mul)
-				top--
-			}
-		case "/":
-			{
-				div := stack[top-2] / stack[top-1]
-				stack = stack[:top-2]
-				stack = append(stack, div)
-				top--
-			}
-		default:
-			{
-				i, _ := strconv.Atoi(v)
-				stack = append(stack, i)
-				top++
+	stack := make([]int, 0, len(tokens))
+	for _, token := range tokens {
+		v, err := strconv.Atoi(token)
+		if err == nil {
+			stack = append(stack, v)
+		} else {
+			num1, num2 := stack[len(stack)-2], stack[len(stack)-1]
+			stack = stack[:len(stack)-2]
+			switch token {
+			case "+":
+				stack = append(stack, num1+num2)
+			case "-":
+				stack = append(stack, num1-num2)
+			case "*":
+				stack = append(stack, num1*num2)
+			case "/":
+				stack = append(stack, num1/num2)
 			}
 		}
 	}
diff --git a/website/content/ChapterFour/0100~0199/0150.Evaluate-Reverse-Polish-Notation.md b/website/content/ChapterFour/0100~0199/0150.Evaluate-Reverse-Polish-Notation.md
@@ -66,46 +66,23 @@ import (
 )
 
 func evalRPN(tokens []string) int {
-	if len(tokens) == 1 {
-		i, _ := strconv.Atoi(tokens[0])
-		return i
-	}
-	stack, top := []int{}, 0
-	for _, v := range tokens {
-		switch v {
-		case "+":
-			{
-				sum := stack[top-2] + stack[top-1]
-				stack = stack[:top-2]
-				stack = append(stack, sum)
-				top--
-			}
-		case "-":
-			{
-				sub := stack[top-2] - stack[top-1]
-				stack = stack[:top-2]
-				stack = append(stack, sub)
-				top--
-			}
-		case "*":
-			{
-				mul := stack[top-2] * stack[top-1]
-				stack = stack[:top-2]
-				stack = append(stack, mul)
-				top--
-			}
-		case "/":
-			{
-				div := stack[top-2] / stack[top-1]
-				stack = stack[:top-2]
-				stack = append(stack, div)
-				top--
-			}
-		default:
-			{
-				i, _ := strconv.Atoi(v)
-				stack = append(stack, i)
-				top++
+	stack := make([]int, 0, len(tokens))
+	for _, token := range tokens {
+		v, err := strconv.Atoi(token)
+		if err == nil {
+			stack = append(stack, v)
+		} else {
+			num1, num2 := stack[len(stack)-2], stack[len(stack)-1]
+			stack = stack[:len(stack)-2]
+			switch token {
+			case "+":
+				stack = append(stack, num1+num2)
+			case "-":
+				stack = append(stack, num1-num2)
+			case "*":
+				stack = append(stack, num1*num2)
+			case "/":
+				stack = append(stack, num1/num2)
 			}
 		}
 	}
