02. 2차원 배열 탐색

문제 풀이

Ch.02 - 01. 큰 수 출력하기

function solution(n, arr) {
  const answer = [];

  arr.reduce((preNum, curNum) => {
    if (preNum < curNum) answer.push(curNum);

    return curNum;
  }, n);

  return answer;
}

Ch.02 - 02. 보이는 학생

function solution(n, arr) {
  let answer = 0;

  arr.reduce((preNum, curNum) => {
    if (preNum < curNum) {
      answer++;
      return curNum;
    }

    return preNum;
  }, n);

  return answer;
}

Ch.02 - 03. 가위 바위 보

function solution(n, arr1, arr2) {
  const victoryConditionsObj = {
    1: 2,
    2: 3,
    3: 1,
  };

  const scoreList = [];

  for (let i = 0; i < n; i++) {
    const tempA = arr1[i];
    const tempB = arr2[i];

    if (tempA === tempB) {
      scoreList.push("D");
    } else {
      scoreList.push(victoryConditionsObj[tempA] === tempB ? "B" : "A");
    }
  }

  return scoreList;
}

Ch.02 - 04. 점수계산

function solution(arr) {
  let answer = 0;

  arr.reduce((acc, cur) => {
    const addPoint = cur ? acc + 1 : 0;
    answer += addPoint;

    return addPoint;
  }, 0);

  return answer;
}

Ch.02 - 05. 등수구하기

function solution(arr) {
  const n = arr.length;
  let answer = new Array(n).fill(1);

  for (let i = 0; i < n; i++) {
    const scoreA = arr[i];
    for (let j = 0; j < n; j++) {
      const scoreB = arr[j];
      if (scoreA < scoreB) answer[i]++;
    }
  }
  return answer;
}

Ch.02 - 06. 격자판 최대합

function solution(n, arr) {
  let answer = 0;

  for (let i = 0; i < n; i++) {
    let rowSum = 0;
    let colSum = 0;
    for (let j = 0; j < n; j++) {
      rowSum += arr[i][j];
      colSum += arr[j][i];
    }
    answer = Math.max(answer, rowSum, colSum);
  }

  {
    let leftCrossSum = 0;
    let rightCrossSum = 0;

    for (let l = 0; l < n; l++) {
      leftCrossSum += arr[l][l];
      rightCrossSum += arr[l][n - l - 1];
    }
    answer = Math.max(answer, leftCrossSum, rightCrossSum);
  }

  return answer;
}

Ch.02 - 07. 봉우리

function solution(n, arr) {
  let answer = 0;

  for (let i = 0; i < n; i++) {
    for (let j = 0; j < n; j++) {
      const curHeight = arr[i][j];

      const eastHeight = arr[i]?.[j - 1] || 0;
      const westHeight = arr[i]?.[j + 1] || 0;
      const southHeight = arr[i + 1]?.[j] || 0;
      const northHeight = arr[i - 1]?.[j] || 0;

      if (
        eastHeight < curHeight &&
        westHeight < curHeight &&
        southHeight < curHeight &&
        northHeight < curHeight
      ) {
        answer++;
      }
    }
  }

  return answer;
}