55 lines
1.3 KiB
JavaScript
55 lines
1.3 KiB
JavaScript
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/* eslint-disable */
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// 四则运算
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!(function () {
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var calculate = function (s) {
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s = s.trim();
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const stack = new Array();
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let preSign = '+';
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let numStr = '';
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const n = s.length;
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for (let i = 0; i < n; ++i) {
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if (s[i] === '.' || (!isNaN(Number(s[i])) && s[i] !== ' ')) {
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numStr += s[i];
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} else if (s[i] === '(') {
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let isClose = 1;
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let j = i;
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while (isClose > 0) {
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j += 1;
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if (s[j] === '(') isClose += 1;
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if (s[j] === ')') isClose -= 1;
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}
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numStr = `${calculate(s.slice(i + 1, j))}`;
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i = j;
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}
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if ((isNaN(Number(s[i])) && s[i] !== '.') || i === n - 1) {
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let num = parseFloat(numStr);
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switch (preSign) {
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case '+':
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stack.push(num);
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break;
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case '-':
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stack.push(-num);
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break;
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case '*':
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stack.push(stack.pop() * num);
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break;
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case '/':
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stack.push(stack.pop() / num);
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break;
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default:
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break;
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}
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preSign = s[i];
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numStr = '';
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}
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}
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let ans = 0;
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while (stack.length) {
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ans += stack.pop();
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}
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return ans;
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};
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module.exports = calculate;
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})();
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