题解 | #合并表记录#

两种垃圾写法：

1. 先用HashMap合并，再用Vec排序，哈哈哈，好顺手，就是写的多。

use std::io::{self, *};
use std::str::FromStr;
use std::collections::HashMap;
use std::cmp::Ordering;

fn main(){
    let stdin = io::stdin();
    let mut n = 0usize;
    let mut map : HashMap<i32,i32>= HashMap::new();
    let mut index = 0i32;
    let mut value = 0i32;
    
    for line in stdin.lock().lines(){
        let ll = line.unwrap();//String
        if n == 0 {
            n = usize::from_str(ll.as_str()).unwrap();
        }else{
            let numbers: Vec<&str> = ll.split(" ").collect();
            index = numbers[0].trim().parse::<i32>().unwrap_or(0);
            value = numbers[1].trim().parse::<i32>().unwrap_or(0);
            value = match map.get(&index) {
                None => value,
                Some(&old) => value + old,
            };
            map.insert(index, value);
        }
    }
    let mut v : Vec<(i32,i32)> = vec![];
    
    for (key, val) in map.iter() {
        v.push((*key,*val));
    }
    v.sort_by(|(a,c),(b,d)| a.cmp(&b));
    for (key, val) in v.iter() {
        println!("{} {}",key,val);
    }
}

2. 无脑Vec：插入之后排序再 remove()

use std::io::{self, *};
use std::str::FromStr;
use std::cmp::Ordering;

fn main(){
    let stdin = io::stdin();
    let mut n = 0usize;
    let mut index = 0i32;
    let mut value = 0i32;
    let mut v : Vec<(i32,i32)> = vec![];
    
    for line in stdin.lock().lines(){
        let ll = line.unwrap();//String
        if n == 0 {
            n= 1;
        }else{
            let numbers: Vec<&str> = ll.split(" ").collect();
            index = numbers[0].trim().parse::<i32>().unwrap_or(0);
            value = numbers[1].trim().parse::<i32>().unwrap_or(0);
            v.push((index,value));
        }
    }
    v.sort_by(|(a,c),(b,d)| a.cmp(&b));
    for i in (1..v.len()).rev(){
        if v[i].0 == v[i-1].0 {
            v[i-1].1 += v[i].1;
            v.remove(i);
        }
    }
    for (key, val) in v.iter() {
        println!("{} {}",key,val);
    }
}

我属实拉胯！