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Merge pull request #993 from hutbzc/master

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优化150.逆波兰表达式求值中字符串判断逻辑
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程序员Carl
2022-01-11 10:18:26 +08:00
committed by GitHub
parent efe0bebd33 bc41a0044f
commit 26a6a8f1ff
1 changed files with 13 additions and 26 deletions
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problems/0150.逆波兰表达式求值.md
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@ -133,39 +133,26 @@ public:
java: java:
```Java ```Java
public class EvalRPN { class Solution {
public int evalRPN(String[] tokens) { public int evalRPN(String[] tokens) {
Deque<Integer> stack = new LinkedList(); Deque<Integer> stack = new LinkedList();
for (String token : tokens) { for (int i = 0; i < tokens.length; ++i) {
char c = token.charAt(0); 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 (!isOpe(token)) { stack.push(stack.pop() + stack.pop()); // 注意 - 和/ 需要特殊处理
stack.addFirst(stoi(token)); } else if ("-".equals(tokens[i])) {
} else if (c == '+') { stack.push(-stack.pop() + stack.pop());
stack.push(stack.pop() + stack.pop()); } else if ("*".equals(tokens[i])) {
} else if (c == '-') { stack.push(stack.pop() * stack.pop());
stack.push(- stack.pop() + stack.pop()); } else if ("/".equals(tokens[i])) {
} else if (c == '*') { int temp1 = stack.pop();
stack.push( stack.pop() * stack.pop()); int temp2 = stack.pop();
stack.push(temp2 / temp1);
} else { } else {
int num1 = stack.pop(); stack.push(Integer.valueOf(tokens[i]));
int num2 = stack.pop();
stack.push( num2/num1);
} }
} }
return stack.pop(); return stack.pop();
} }
private boolean isOpe(String s) {
return s.length() == 1 && s.charAt(0) <'0' || s.charAt(0) >'9';
}
private int stoi(String s) {
return Integer.valueOf(s);
}
public static void main(String[] args) {
new EvalRPN().evalRPN(new String[] {"10","6","9","3","+","-11","*","/","*","17","+","5","+"});
}
} }
``` ```