/**
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* 将用户输入的连续单个数字合并为一个数
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* @param {Array} expressions - 记录计算表达式的数组
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* @returns {Array} 新的数组
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*/
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export const mergeNumberOfExps = (expressions) => {
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const res: any = [];
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const isNumChar = (n) => /^[\d|.]$/.test(n);
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for (let i = 0; i < expressions.length; i++) {
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if (i > 0 && isNumChar(expressions[i - 1]) && isNumChar(expressions[i])) {
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res[res.length - 1] += expressions[i];
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continue;
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}
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res.push(expressions[i]);
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}
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return res;
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};
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/**
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* 校验表达式是否符合计算法则
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* @param {Array} expressions - 合并数字后的表达式数组
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* @returns {boolean}
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*/
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export const validExp = (expressions, mergeNum = true) => {
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const temp = mergeNum ? mergeNumberOfExps(expressions) : expressions;
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const arr = temp.filter((t) => !'()'.includes(t));
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// 去括号后 length应该为奇数 并且第一个字符和最后一个字符应该为数字而非计算符号
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if (temp.length % 2 === 0 || arr.length % 2 === 0 || Number.isNaN(+arr[0]) || Number.isNaN(+arr[arr.length - 1])) {
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return false;
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}
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for (let i = 0; i < arr.length - 1; i += 2) {
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if (typeof +arr[i] !== 'number' || !Number.isNaN(+arr[i + 1])) return false;
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}
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return true;
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};
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export const validDateExp = (expressions, mergeNum = true) => {
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const temp = mergeNum ? mergeNumberOfExps(expressions) : expressions;
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// length应该3的倍数、 以+/-号开头、以y/m/d/h/m/s结尾、中间应该为数字
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if (temp.length % 3 !== 0) {
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return false;
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}
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for (let i = 0; i < temp.length - 1; i += 3) {
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if (/^\+\d+|-\d+$/.test(temp[i]) || Number.isNaN(+temp[i + 1])) return false;
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}
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return true;
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};
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/**
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* 校验日期计算表达式是否符合计算法则
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* @param {Array} expressions - 合并数字后的表达式数组
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* @returns {boolean}
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*/
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/**
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* 中缀转后缀（逆波兰 Reverse Polish Notation）
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* @param {Array} exps - 中缀表达式数组
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*/
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export const toRPN = (exps) => {
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const s1: any[] = []; // 符号栈
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const s2: any[] = []; // 输出栈
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const getTopVal = (stack) => (stack.length > 0 ? stack[stack.length - 1] : null);
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const levelCompare = (c1, c2) => {
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const getIndex = (c) => ['+-', '×÷', '()'].findIndex((t) => t.includes(c));
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return getIndex(c1) - getIndex(c2);
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};
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exps.forEach((t) => {
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if (typeof t === 'string' && Number.isNaN(Number(t))) {
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// 是符号
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if (t === '(') {
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s1.push(t);
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} else if (t === ')') {
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let popVal;
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do {
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popVal = s1.pop();
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popVal !== '(' && s2.push(popVal);
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} while (s1.length && popVal !== '(');
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} else {
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let topVal = getTopVal(s1);
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if (topVal) {
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while (topVal && topVal !== '(' && levelCompare(topVal, t) >= 0) {
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// 优先级 >= t 弹出到s2
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s2.push(s1.pop());
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topVal = getTopVal(s1);
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}
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s1.push(t);
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} else {
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// s1 为空 直接push
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s1.push(t);
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}
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}
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return;
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}
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s2.push(t); // 数字直接入栈
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});
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while (s1.length) {
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s2.push(s1.pop());
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}
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return s2;
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};
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/**
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* 计算后缀表达式的值
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* @param {Array} rpnExps - 后缀表达式
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*/
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export const calcRPN = (rpnExps) => {
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rpnExps = [...rpnExps];
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const calc = (x, y, type) => {
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const a1 = Number(x);
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const a2 = Number(y);
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switch (type) {
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case '+': {
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return a1 + a2;
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}
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case '-': {
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return a1 - a2;
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}
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case '÷': {
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return a1 / a2;
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}
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case '×': {
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return a1 * a2;
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}
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}
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};
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for (let i = 2; i < rpnExps.length; i++) {
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if ('+-×÷'.includes(rpnExps[i])) {
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const val = calc(rpnExps[i - 2], rpnExps[i - 1], rpnExps[i]);
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rpnExps.splice(i - 2, 3, val);
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i = i - 2;
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}
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}
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return rpnExps[0];
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};
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