https://www.nowcoder.com/questionTerminal/3cd4621963e8454594f00199f4536bb1?answerType=1&f=discussion
我的解法：耗时比较久
const rl = require("readline").createInterface({ input: process.stdin });
let max = 1;
rl.on("line", function (input) {
for (let i = 0; i < input.length; i++) {
let cha = input[i];
let last_index = input.lastIndexOf(cha);
if (i < last_index) {
for (k = last_index; i < k; k--) {
let sub_str = input.slice(i, k + 1);
if (
sub_str.length > max &&
input[i] === input[k] &&
isLoop(sub_str)
) {
max = sub_str.length;
}
}
}
}
console.log(max);
});
function isLoop(str) {
let left = 0,
right = str.length - 1;
while (left < right) {
if (str[left] !== str[right]) return false;
left++;
right--;
}
return true;
}
别人的解法，耗时内存都减半
var readline = require('readline')
const rl = readline.createInterface({
input: process.stdin,
output: process.stdout
})
rl.on('line', (str)=> {
var max = 0;
// 当最长回文子串的长度是奇数时
for(let i=0; i<str.length; i++){
let n = i-1;
let m = i+1;
while(n>=0 && m<str.length && str[n] == str[m]){
max = Math.max(m-n+1, max);
n--;
m++;
}
}
// 当最长回文子串的长度是偶数时
for(let i=0; i<str.length; i++){
let n = i;
let m = i+1;
while(n>=0 && m<str.length && str[n] == str[m]){
max = Math.max(m-n+1, max);
n--;
m++;
}
}
console.log(max);
})
