jumpgame.js

function jump(arr) {
  let cur = 0;
  const target = arr.length - 1;
  
  if(cur >= target) return true;
  while(cur < target) {
    const r = arr[cur];
    if(r <= 0) return false;
    if(cur + r >= target) return true;
    let o = 0, s = cur;
    for(let i = 1; i <= r; i++) {
      if(o < cur + i + arr[cur + i]) {
        o = cur + i + arr[cur + i];
        s = cur + i;
      }
    }
    if(cur < s) cur = s;
    else return false;
  }
  return true;
}

console.log(jump([2, 3, 1, 1, 4]))
console.log(jump([3, 2, 1, 0, 4]))
console.log(jump([3, 2, 2, 0, 4]))