idea1) 상하좌우 이동
idea2) 가장자리로 갔을 때
function solution(arr) {
let answer = 0;
let n = arr.length;
let dx = [-1, 0, 1, 0];
let dy = [0, 1, 0, -1];
for (let i = 0; i < n; i++) {
for (let j = 0; j < n; j++) {
let flag = true;
for (let k = 0; k < 4; k++) {
let nx = i + dx[k];
let ny = j + dy[k];
if (nx >= 0 && nx < n && ny >= 0 && ny < n && arr[nx][ny] >= arr[i][j]) {
flag = false;
break;
}
}
if (flag) answer++;
}
}
return answer;