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Copy pathBasicCalculatorII.V2.js
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60 lines (53 loc) · 1.42 KB
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// https://leetcode-cn.com/problems/basic-calculator-ii/
var Test = require('../Common/Test');
var calculate = function (s) {
const tokens = s.replace(/ /g, '').replace(/([-/+*])/g, " $1 ").split(' ');
tokens.push('$');
const priorities = {
'$': 0,
'+': 1,
'-': 1,
'*': 2,
'/': 2,
};
const rpn = [];
const ops = [];
for (const token of tokens) {
if (/\d+/.test(token)) {
rpn.push(token);
}
else {
while (ops.length > 0 && priorities[token] <= priorities[ops[ops.length - 1]]) {
rpn.push(ops.pop());
}
ops.push(token);
}
}
return eval(rpn);
function eval(tokens) {
const stack = [];
for (const token of tokens) {
if ("+-*/".includes(token)) {
stack.push(((a, b) => {
switch (token) {
case '+': return b + a;
case '-': return b - a;
case '*': return b * a;
case '/': return Math.trunc(b / a);
}
})(stack.pop(), stack.pop()));
}
else {
stack.push(Number(token));
}
}
return stack[0];
};
};
function test(s) {
Test.test(calculate, s);
}
test("3+2*2");
test(" 3/2 ");
test(" 3+5 / 2 ");
test("1+1+1");