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01. 기본 문제 풀이

문제 풀이​

Ch.01 - 01. 세 수 중 최솟값​

function solution(a, b, c) {
  let answer = a;

  if (answer > b) answer = b;
  if (answer > c) answer = c;

  return answer;
}

Ch.01 - 02. 삼각형 판별하기​

function solution(a, b, c) {
  const totalNum = a + b + c;
  let maxNum = a;

  if (maxNum < b) maxNum = b;
  if (maxNum < c) maxNum = c;

  return totalNum - maxNum * 2 > 0 ? "YES" : "NO";
}

Ch.01 - 03. 연필 개수​

function solution(n) {
  return Math.ceil(n / 12);
}

Ch.01 - 04. 1부터 N까지 합 출력하기​

function solution(n) {
  let answer = 0;

  for (let i = 1; i <= n; i++) {
    answer += i;
  }

  return answer;
}

Ch.01 - 05. 최솟값 구하기​

function solution(arr) {
  return arr.reduce((a, b) => (a > b ? b : a), Number.MAX_SAFE_INTEGER);
}

Ch.01 - 06. 홀수​

function solution(arr) {
  let sumOddNum = 0;
  let minOddNum = Number.MAX_SAFE_INTEGER;

  for (let curNum of arr) {
    if (curNum % 2) {
      sumOddNum += curNum;
      if (curNum < minOddNum) minOddNum = curNum;
    }
  }

  return [sumOddNum, minOddNum];
}

Ch.01 - 07. 10부제​

function solution(n, arr) {
  return arr.reduce((acc, cur) => {
    if (cur % 10 === n) acc += 1;

    return acc;
  }, 0);
}

Ch.01 - 08. 일곱 난쟁이​

function solution(arr) {
  const dwarfList = [...arr];
  const overNum = dwarfList.reduce((acc, cur) => acc + cur, 0) - 100;

  for (let i = 0; i < arr.length; i++) {
    const firstDwarf = dwarfList[i];
    for (let j = i + 1; j < arr.length; j++) {
      const secondDwarf = dwarfList[j];

      if (firstDwarf + secondDwarf === overNum) {
        dwarfList.splice(i, 1);
        dwarfList.splice(j, 1);
      }
    }
  }
  return dwarfList;
}

Ch.01 - 09. A를 #으로​

function solution(str) {
  let answer = "";

  for (let i = 0; i < str.length; i++) {
    answer += str[i] === "A" ? "#" : str[i];
  }

  return answer;
}

Ch.01 - 10. 문자 찾기​

function solution(str, char) {
  let count = 0;

  for (let i = 0; i < str.length; i++) {
    if (str[i] === char) count++;
  }

  return count;
}

Ch.01 - 11. 대문자 찾기​

function solution(str) {
  let answer = 0;

  for (let i = 0; i < str.length; i++) {
    const convertAsciiCode = str[i].charCodeAt();
    if (65 <= convertAsciiCode && convertAsciiCode <= 90) answer++;
  }

  return answer;
}

Ch.01 - 12. 대문자로 통일​

function solution(str) {
  let answer = "";

  for (let i = 0; i < str.length; i++) {
    const convertAsciiCode = str[i].charCodeAt();

    answer +=
      97 <= convertAsciiCode && convertAsciiCode <= 122
        ? String.fromCharCode(convertAsciiCode - 32)
        : str[i];
  }

  return answer;
}

Ch.01 - 13. 대소문자 변환​

function solution(str) {
  let answer = "";

  for (let i = 0; i < str.length; i++) {
    const convertAsciiCode = str[i].charCodeAt();

    if (65 <= convertAsciiCode && convertAsciiCode <= 90) {
      answer += String.fromCharCode(convertAsciiCode + 32);
    } else if (97 <= convertAsciiCode && convertAsciiCode <= 122) {
      answer += String.fromCharCode(convertAsciiCode - 32);
    }
  }

  return answer;
}

Ch.01 - 14. 가장 긴 문자열​

// function solution(arr) {
// return arr.reduce((acc, cur) => (acc.length < cur.length ? cur : acc), "");
// }

Ch.01 - 15. 가운데 문자 출력​

function solution(str) {
  const centerIdx = Math.ceil(str.length / 2 - 1);

  return str.substring(centerIdx, centerIdx + (str.length % 2 ? 1 : 2));
}

Ch.01 - 16. 중복문자제거​

function solution(str) {
  const cacheObj = {};

  for (let i = 0; i < str.length; i++) {
    const curChar = str[i];

    if (!cacheObj[curChar]) cacheObj[curChar] = true;
  }

  return Object.keys(cacheObj).join("");
}

Ch.01 - 17. 중복단어제거​

function solution(arr) {
  const cacheObj = {};

  for (let i = 0; i < arr.length; i++) {
    const curChar = arr[i];

    if (!cacheObj[curChar]) cacheObj[curChar] = true;
  }

  return Object.keys(cacheObj);
}