题解 | #字符串最后一个单词的长度#

var str = readline().trim(); // readline() , 从控制台读取数据
var length = str.length;
var ch, index = 0;
while(index < length) {
    ch = str[length - (index + 1)];
    if (ch === ' ') {
        break;
    }
    index++;
}

console.log(index)