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修改0150逆波兰表达式求值 Java版本

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将for循环改为for each，使代码更加简洁。因为循环除了对token进行遍历，i并没有其他用途。
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lizhendong128
2022-05-19 11:08:59 +08:00
parent 6c0d4365c6
commit 0b88af0824
1 changed files with 6 additions and 6 deletions
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12
problems/0150.逆波兰表达式求值.md
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@ -136,19 +136,19 @@ java:
class Solution { class Solution {
public int evalRPN(String[] tokens) { public int evalRPN(String[] tokens) {
Deque<Integer> stack = new LinkedList(); Deque<Integer> stack = new LinkedList();
for (int i = 0; i < tokens.length; ++i) { for (String s : tokens) {
if ("+".equals(tokens[i])) { // leetcode 内置jdk的问题，不能使用==判断字符串是否相等 if ("+".equals(s)) { // leetcode 内置jdk的问题，不能使用==判断字符串是否相等
stack.push(stack.pop() + stack.pop()); // 注意 - 和/ 需要特殊处理 stack.push(stack.pop() + stack.pop()); // 注意 - 和/ 需要特殊处理
} else if ("-".equals(tokens[i])) { } else if ("-".equals(s)) {
stack.push(-stack.pop() + stack.pop()); stack.push(-stack.pop() + stack.pop());
} else if ("*".equals(tokens[i])) { } else if ("*".equals(s)) {
stack.push(stack.pop() * stack.pop()); stack.push(stack.pop() * stack.pop());
} else if ("/".equals(tokens[i])) { } else if ("/".equals(s)) {
int temp1 = stack.pop(); int temp1 = stack.pop();
int temp2 = stack.pop(); int temp2 = stack.pop();
stack.push(temp2 / temp1); stack.push(temp2 / temp1);
} else { } else {
stack.push(Integer.valueOf(tokens[i])); stack.push(Integer.valueOf(s));
} }
} }
return stack.pop(); return stack.pop();