acwing::acwing4216类 参考

AcWing 4216. 图中的环 更多...

#include <acwing.h>

静态 Public 成员函数
static int	main (istream &cin, ostream &cout)

详细描述

AcWing 4216. 图中的环

在文件 acwing.h 第 894 行定义.

成员函数说明

main()

int acwing::acwing4216::main ( istream &  cin, ostream &  cout  )

static

在文件 acwing.cpp 第 2654 行定义.

                                                    {
        unsigned short n;
        unsigned short m;
        unsigned short a;
        unsigned short b;
        cin >> n >> m;
        auto flag = vector(n, false);
        auto edge = vector(n, unordered_set<unsigned short>());
        for(unsigned short i = 0; i < m; i++) {
            cin >> a >> b;
            edge[a - 1].insert(b - 1);
            edge[b - 1].insert(a - 1);
        }
        int circle = 0;
        auto que   = queue<pair<unsigned short, unsigned short>>();
        que.push(pair(0, 0));
        flag[0] = true;
        while(!que.empty()) {
            auto [prev, current] = que.front();
            que.pop();
            for(auto next: edge[current]) {
                if(next != prev) {
                    if(flag[next]) {
                        if(circle == 2) {
                            cout << "NO";
                            return 0;
                        }
                        circle += 1;
                    } else {
                        que.push(pair(current, next));
                        flag[next] = true;
                    }
                }
            }
        }
        for(unsigned short i = 0; i < n; i++) {
            if(!flag[i]) {
                cout << "NO";
                return 0;
            }
        }
        if(circle != 2) {
            cout << "NO";
            return 0;
        }
        cout << "YES";
        return 0;
    }

被这些函数引用 acwing::TEST().

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该类的文档由以下文件生成:

• acwing.h
• acwing.cpp