题解归档 - cf2219B1

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• 本地编号：cf2219B1
• 本地来源：problems/cf2219B1/idea.md
• 题目链接：https://codeforces.com/contest/2219/problem/B1
• 原始标题：cf2219B1 - Unique Values (Easy version)

思路

cf2219B1 - Unique Values (Easy version)

Pattern

The original problem is interactive, but the hacked format provides the whole
array. Therefore no query simulation is needed.

Exactly one value appears three times and all other values appear twice. Store
the positions for every value and print the three positions of the value whose
position list has length 3.

Checks

• python tools/math_reasoning_search.py --problem cf2219B1 -n 5 - required
  precheck done by plan flag.
• Local sample uses the hacked input format rather than the original transcript.

代码

来源：problems/cf2219B1/solution.cpp

#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int T;
    cin >> T;
    while (T--) {
        int n;
        cin >> n;
        vector<vector<int>> pos(n + 1);
        for (int i = 1; i <= 2 * n + 1; i++) {
            int x;
            cin >> x;
            pos[x].push_back(i);
        }
        for (int x = 1; x <= n; x++) {
            if ((int)pos[x].size() == 3) {
                cout << "! " << pos[x][0] << ' ' << pos[x][1] << ' ' << pos[x][2] << '\n';
                break;
            }
        }
    }
    return 0;
}