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| class Solution {
public int evalRPN(String[] tokens) {
Stack<Integer> numStack = new Stack<>();
for (String token : tokens) {
switch (token) {
case "+": {
numStack.push(numStack.pop() + numStack.pop());
break;
}
case "-": {
int b = numStack.pop(), a = numStack.pop();
numStack.push(a - b);
break;
}
case "*": {
numStack.push(numStack.pop() * numStack.pop());
break;
}
case "/": {
int b = numStack.pop(), a = numStack.pop();
numStack.push(a / b);
break;
}
default:
numStack.push(Integer.parseInt(token));
}
}
return numStack.pop();
}
}
|
References
150. Evaluate Reverse Polish Notation
剑指 Offer II 036. 后缀表达式