题解 | #句子逆序#

//双指针
using System;
using System.Text;

namespace HJ11{
    class Solution{
        public static void Main(){
            var input = Console.ReadLine().ToCharArray();
            var len = input.Length;
            var res = new StringBuilder();
            var j = len-1;
            
            for(int i = len-1; i >= 0; i--){              
                if(input[i] == ' '){                
                    for(int k = i+1; k<=j;k++){
                         res.Append(input[k]);
                    }
                    j = i-1;
                    res.Append(' ');                    
                }
                if(i == 0){
                    for(int k = i; k<=j;k++){
                         res.Append(input[k]);
                    }
                }
            }             
            Console.WriteLine(res);
        }
    }
}