csp认证 201503-2 数字排序

解

vector与map结合

map存储数字以及出现个数，利用vector自定义排序函数来排序

//
// Created by 29273 on 2021-04-05.
//
#include "bits/stdc++.h"

using namespace std;

bool cmp(pair<int, int> p1, pair<int, int> p2) {
    if (p1.second == p2.second) {
        return p1.first < p2.first;
    }
    return p1.second > p2.second;
}

int main() {
    int n, a;
    unordered_map<int, int> m;
    vector<pair<int, int>> v;
    cin >> n;
    for (int i = 0; i < n; ++i) {
        cin >> a;
        m[a]++;
    }
    for (auto it:m) {
        v.emplace_back(it);
    }
    sort(v.begin(), v.end(), cmp);
    for (auto it:v) {
        printf("%d %d\n", it.first, it.second);
    }
    return 0;
}