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由于 $1 - 10$ 十个数字只能出现 $n / 10$ 次，依次枚举 $1 - 10$的前 $n / 10$个最小的代价

若某数的代价次数小于等于 $n / 10$，必须全选，直接跳过

附C++，Java，Python3，JavaScript，Go代码

C++代码：（运行时间：648 ms，运行空间：944 KB）

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;

typedef long long LL;
vector<vector<int>> s(10);
int n, a, b;

int main() 
{
    cin >> n;
    for (int i = 0; i < n; i ++) {
        cin >> a >> b;
        s[a].push_back(b);
    }
    for (int i = 0; i < 10; i ++)
        sort(s[i].begin(), s[i].end());

    LL res = 0, c = n / 10;
    for (int i = 0; i < 10; i ++) {
        if (s[i].size() <= c)   continue;

        for (int j = 0; j < s[i].size() - c; j ++)
            res += s[i][j];
    }
    cout << res << endl;
    return 0;
}

Java代码：（运行时间：4985 ms，运行空间：45572 KB）

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        List<Integer>[] s = new ArrayList[10];
        Arrays.setAll(s, l -> new ArrayList<>());
        for (int i = 0; i < n; i ++) {
            int a = sc.nextInt(), b = sc.nextInt();
            s[a].add(b);
        }
        for (int i = 0; i < 10; i ++) {
            Collections.sort(s[i]);
        }

        int c = n / 10;
        long res = 0;
        for (int i = 0; i < 10; i ++) {
            if (s[i].size() <= c)   continue;
            for (int j = 0; j < s[i].size() - c; j ++) {
                res += s[i].get(j);
            }
        }
        System.out.println(res);
    }
}

Python3代码：（运行时间：2455 ms，运行空间：45636 KB）

n = int(input())
s = [[] for i in range(10)]
for i in range(n):
    a, b = map(int, input().split())
    s[a].append(b)
for i in range(10):
    s[i].sort()

res, c = 0, n // 10
for i in range(10):
    if len(s[i]) > c:
        res += sum(s[i][:len(s[i]) - c])

print(res)

JavaScript代码：（运行时间：2200 ms，运行空间：32280 KB）

const readline = require('readline');

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});
const s = Array.from({ length: 10 }, () => []);
let n;
rl.on('line', (input) => {
    if (!n) {
        n = Number(input.trim());
    } else {
        const [a, b] = input.trim().split(' ').map(Number);
        s[a].push(b);
    }
});
rl.on('close', () => {
    for (let i = 0; i < 10; i ++) {
        s[i].sort((a, b) => a - b);
    }
    let res = 0, c = Math.floor(n / 10);
    for (let i = 0; i < 10; i ++) {
        if (s[i].length <= c)   continue;

        for (let j = 0; j < s[i].length - c; j ++) {
            res += s[i][j];
        }
    }
    console.log(res);
});

Go代码：（运行时间：812 ms，运行空间：10464 KB）

package main

import (
    . "fmt"
    "bufio"
    "os"
    "sort"
)

const N int = 10

var (
    in = bufio.NewReader(os.Stdin)
    out = bufio.NewWriter(os.Stdout)
    s = make([][] int, N)
    n, a, b int
)

func main() {
    defer out.Flush()
    Fscan(in, &n)
    for i := 0; i < n; i ++ {
        Fscan(in, &a, &b)
        s[a] = append(s[a], b)
    }
    for i := 0; i < 10; i ++ {
        sort.Slice(s[i], func(x, y int) bool { return s[i][x] < s[i][y] })
    }
    res, c := 0, n / 10
    for i := 0; i < 10; i ++ {
        if len(s[i]) <= c {
            continue
        }
        for j := 0; j < len(s[i]) - c; j ++ {
            res += s[i][j]
        }
    }
    Fprintln(out, res)
}