[백준 | 실버 1 | JavaScript] 2468번, 안전 영역

 

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2468번 - 안전 영역

 

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문제

풀이

(1) DFS 재귀 구현

let input = require("fs").readFileSync("/dev/stdin").toString().trim().split("\n");

let idx = 0;
const N = Number(input[idx++]);
const map = [];
let maxAnswer = 0;

const dn = [0, 1, 0, -1];
const dm = [1, 0, -1, 0];

for (let n = 0; n < N; n++) {
  let row = input[idx++].split(" ").map(Number);
  map.push(row);
}

const flatMap = map.flat();
const minValue = Math.min(...flatMap);
const maxValue = Math.max(...flatMap);

const checked = (n, m) => {
  return n < 0 || m < 0 || n >= N || m >= N;
};

const dfsRecursive = (n, m, visited, value) => {
  visited[n][m] = true;

  for (let d = 0; d < 4; d++) {
    const tn = n + dn[d];
    const tm = m + dm[d];

    if (checked(tn, tm)) continue;
    if (visited[tn][tm]) continue;
    if (map[tn][tm] <= value) continue;

    dfsRecursive(tn, tm, visited, value);
  }
};

for (let v = 0; v <= maxValue; v++) {
  const visited = Array.from({ length: N }, () =>
    Array.from({ length: N }, () => false)
  );
  let cnt = 0;

  for (let n = 0; n < N; n++) {
    for (let m = 0; m < N; m++) {
      if (visited[n][m]) continue;
      if (map[n][m] <= v) continue;

      cnt += 1;
      dfsRecursive(n, m, visited, v);
    }
  }

  maxAnswer = Math.max(maxAnswer, cnt);
}

console.log(maxAnswer);