题解 | 小红的正整数计数

const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

void async function () {
    let line = await readline()
    line = line.split(' ').map(a=>parseInt(a))
     let left = line[0]
     let right = line[1]
     let length = right-left+1

     if(left%2===1 && right%2 === 1){
        console.log((length-1)/2)
     }else if(left%2===0 && right%2===0){
        console.log((length+1)/2)
     }else{
        console.log(length/2)
     }
}()

笨笨的方法之分类讨论