五行学说(Five Elements) 题解

思路分析

按题目要求使用对应数据结构与算法模拟/递推求解，注意数据范围边界与时间复杂度。

参考代码

#include <iostream>
#include <vector>
#include <numeric>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    if (!(cin >> n >> m)) return 0;
    vector<int> p(n + 1), d(n + 1, 0);
    iota(p.begin(), p.end(), 0);
    auto find = [&](auto& self, int x) -> int {
        if (p[x] == x) return x;
        int r = self(self, p[x]);
        d[x] = (d[x] + d[p[x]]) % 5;
        return p[x] = r;
    };
    int bad = 0;
    for (int i = 0; i < m; ++i) {
        char op;
        int x, y;
        if (!(cin >> op >> x >> y)) break;
        if (x < 1 || x > n || y < 1 || y > n || x == y) {
            ++bad;
            continue;
        }
        int rel = (op == 's') ? 1 : 2;
        int rx = find(find, x), ry = find(find, y);
        if (rx == ry) {
            if ((d[y] - d[x] + 5) % 5 != rel) ++bad;
        } else {
            p[ry] = rx;
            d[ry] = (d[x] + rel - d[y] + 5) % 5;
        }
    }
    cout << bad << "\n";
    return 0;
}