标签：blog http 使用 io for ar div line
Evaluate the value of an arithmetic expression in Reverse Polish Notation.
Valid operators are +, -, *, /. Each operand may be an integer or another expression.
Some examples:
["2", "1", "+", "3", "*"] -> ((2 + 1) * 3) -> 9 ["4", "13", "5", "/", "+"] -> (4 + (13 / 5)) -> 6
说明：使用一个数字栈即可。（也可用数组链表模拟栈）
inline int newPop(stack<int> &digits) {
int v = digits.top();
digits.pop();
return v;
}
class Solution {
public:
int evalRPN(vector<string> &tokens) {
stack<int> digits;
for(size_t id = 0; id < tokens.size(); ++id) {
if((tokens[id][0] == ‘-‘ && tokens[id].size() > 1 ) ||
(tokens[id][0] >= ‘0‘ && tokens[id][0] <= ‘9‘)) digits.push(atoi(tokens[id].c_str()));
else
{
int v;
switch(tokens[id][0]){
case ‘+‘: {
digits.push(newPop(digits)+newPop(digits));
break;
}
case ‘-‘: {
v = newPop(digits);
digits.push(newPop(digits)-v);
break;
}
case ‘*‘: {
digits.push(newPop(digits)*newPop(digits));
break;
}
case ‘/‘: {
v = newPop(digits);
digits.push(newPop(digits)/v);
break;
}
}
}
}
return digits.top();
}
};
Evaluate Reverse Polish Notation,布布扣,bubuko.com
Evaluate Reverse Polish Notation
标签：blog http 使用 io for ar div line
原文地址：http://www.cnblogs.com/liyangguang1988/p/3902247.html
