baekjoon 1935 후위 표기식2(nodejs)

Maliethy·2021년 12월 11일

baekjoon 1935 utf 유니코드 후위 표기식2

algorithm

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5/5

1. 틀린 코드

// 후위 표기식2


// const question = `1
// AA+A+
// 1`;

const question = `5
ABC*+DE/-
1
2
3
4
5`;

const fs = require("fs");
const input = (
  process.platform === "linux"
    ? fs.readFileSync("/dev/stdin").toString()
    : question
).split("\n");

// console.log(3 * 2 + 1 - 4 / 5);
//[A,B,C,*,+,D,E,/,-]
// B * C + A - D / E

let idx = 0,
  nStack = [];
const strArr = input[1].split("");
const numArr = input.slice(2).map((n) => +n);

// console.log("strArr", strArr);
// console.log("numArr", numArr);

strArr.map((str) => {
  let signal = "";
  if (str === "+" || str === "-" || str === "*" || str === "/") {
    signal = str;
  } else {
    nStack.push(numArr[idx] ? numArr[idx++] : numArr[--idx]);
  }

  // console.log(idx, nStack, signal);
  if (signal && nStack.length > 1) {
    let second = nStack.pop(),
      first = nStack.pop();

    if (signal === "+") {
      nStack.push(first + second);
    } else if (signal === "-") {
      nStack.push(first - second);
    } else if (signal === "*") {
      nStack.push(first * second);
    } else {
      nStack.push(first / second);
    }
    signal = "";
  }
});
// console.log("nStack", nStack);

console.log(nStack[0].toFixed(2));

2. 맞은 코드

// 후위 표기식2


// const question = `1
// AA+A+
// 1`;

const question = `5
ABC*+DE/-
1
2
3
4
5`;

const fs = require("fs");
const input = (
  process.platform === "linux"
    ? fs.readFileSync("/dev/stdin").toString()
    : question
).split("\n");

const n = Number(input[0]);
const str = input[1];
const stack = [];
const alpha = [];
alpha.length = n;
const nums = [];
nums.length = n;

for (let i = 0; i < n; i++) {
  nums[i] = Number(input[i + 2]);
}
// console.log(nums); //[ 1, 2, 3, 4, 5 ]
let cnt = 0;
for (let i = 0; i < str.length; i++) {
  if (str[i].charCodeAt() >= 65) {
    const alphaIndex = Number(str[i].charCodeAt() - 65);
    if (!alpha[alphaIndex]) {
      alpha[alphaIndex] = nums[cnt++];
    }
    stack.push(alpha[alphaIndex]);
    continue;
  }
  // console.log(stack);
  // [ 1, 2, 3 ]
  // [ 1, 6 ]
  // [ 7, 4, 5 ]
  // [ 7, 0.8 ]
  const operator = str[i];
  const y = stack.pop();
  const x = stack.pop();
  switch (operator) {
    case "+":
      stack.push(x + y);
      break;
    case "-":
      stack.push(x - y);
      break;
    case "*":
      stack.push(x * y);
      break;
    case "/":
      stack.push(x / y);
      break;
  }
}
console.log(stack.pop().toFixed(2));