题解 | #密码截取#速度80%：两边拓展精简写法

  let arr = str.split("");
  let len = arr.length;
  let max = 0
  for(let i = 0;i<len;i++){
      let a = i,b = i+1
      while(a>=0&&b<len&&arr[a--]==arr[b++]){
          if(b-a-1>max){
              max = b-a-1
          }
      }
      
      let c = i,d = i+2
      while(c>=0&&d<len&&arr[c--]==arr[d++]){
          if(d-c-1>max){
              max = d-c-1
          }
      }
  }
  console.log(max);
}
max(readline());