hdu 1704 poj 3660 (floyd求傳遞閉包)

hdu 1704

題意：
n個人，給m行a，b， 表示a能擊敗b，現在問你最多有多少個兩人勝負的詢問還不能確定。

floyd過後遍歷每對關係，如果G[i][j]和G[j][i]都是0，那就不能確定。

/**
* Author : zzy
* Date : 2020-04-19-19.12.20 Sunday
*/
#include <bits/stdc++.h>

#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define forn(i, n) for (int i = 0; i < (int)(n); ++i)
#define for1(i, n) for (int i = 1; i <= (int)(n); ++i)
#define ford(i, a, b) for (int i = (int)(a); i >= (int)b; --i)
#define fore(i, a, b) for (int i = (int)(a); i <= (int)(b); ++i)
#define rep(i, l, r) for (int i = (l); i <= (r); i++)
#define per(i, r, l) for (int i = (r); i >= (l); i--)
#define ms(x, y) memset(x, y, sizeof(x))
#define SZ(x) ((int)(x).size())

using namespace std;

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector<vi> vvi;
typedef long long i64;
typedef vector<i64> vi64;
typedef vector<vi64> vvi64;
typedef pair<i64, i64> pi64;
typedef double ld;

template<class T> bool uin(T &a, T b) { return a > b ? (a = b, true) : false; }
template<class T> bool uax(T &a, T b) { return a < b ? (a = b, true) : false; }

const int maxn = 600;
int tc, n, m, G[maxn][maxn];

void floyd() {
    for (int k = 1; k <= n; ++k) {
        for (int i = 1; i <= n; ++i) {
            if (G[i][k]) {
                for (int j = 1; j <= n; ++j) {
                    if (G[k][j]) {
                        G[i][j] = 1;
                    }
                }
            }
        }
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.precision(10);
    cout << fixed;
#ifdef LOCAL_DEFINE
    freopen("input.txt", "r", stdin);
#endif

    cin >> tc;
    while (tc--) {
        ms(G, 0);
        cin >> n >> m;
        forn(i, m) {
            int a, b;
            cin >> a >> b;
            G[a][b] = 1;
        }
        floyd();
        int cnt = 0;
        for (int i = 1; i <= n; ++i) {
            for (int j = i+1; j <= n; ++j) {
                if (!G[i][j] && !G[j][i]) ++cnt;
            }
        }
        cout << cnt << '\n';
    }

#ifdef LOCAL_DEFINE
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
    return 0;
}

poj 3660

題意：
輸入和hdu1704一樣，問你有多少個人可以確定排名。

遍歷一下某個數是不是和除了他之外的所有數都有關係就行。

/**
* Author : zzy
* Date : 2020-04-19-19.12.20 Sunday
*/
#include <stdio.h>
#include <vector>
#include <algorithm>
#include <string.h>
#include <limits.h>
#include <string>
#include <iostream>
#include <queue>
#include <math.h>
#include <map>
#include <stack>
#include <set>
#include <vector>

#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define forn(i, n) for (int i = 0; i < (int)(n); ++i)
#define for1(i, n) for (int i = 1; i <= (int)(n); ++i)
#define ford(i, a, b) for (int i = (int)(a); i >= (int)b; --i)
#define fore(i, a, b) for (int i = (int)(a); i <= (int)(b); ++i)
#define rep(i, l, r) for (int i = (l); i <= (r); i++)
#define per(i, r, l) for (int i = (r); i >= (l); i--)
#define ms(x, y) memset(x, y, sizeof(x))
#define SZ(x) ((int)(x).size())

using namespace std;

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector<vi> vvi;
typedef long long i64;
typedef vector<i64> vi64;
typedef vector<vi64> vvi64;
typedef pair<i64, i64> pi64;
typedef double ld;

template<class T> bool uin(T &a, T b) { return a > b ? (a = b, true) : false; }
template<class T> bool uax(T &a, T b) { return a < b ? (a = b, true) : false; }

const int maxn = 200;
int tc, n, m, G[maxn][maxn];

void floyd() {
    for (int k = 1; k <= n; ++k) {
        for (int i = 1; i <= n; ++i) {
            if (G[i][k]) {
                for (int j = 1; j <= n; ++j) {
                    if (G[k][j]) {
                        G[i][j] = 1;
                    }
                }
            }
        }
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.precision(10);
    cout << fixed;
#ifdef LOCAL_DEFINE
    freopen("input.txt", "r", stdin);
#endif

    ms(G, 0);
    cin >> n >> m;
    forn(i, m) {
        int a, b;
        cin >> a >> b;
        G[a][b] = 1;
    }
    floyd();
    int ans = 0;
    for (int i = 1; i <= n; ++i) {
        int cnt = 0;
        for (int j = 1; j <= n; ++j) {
            if (G[i][j] == 1 || G[j][i] == 1) ++cnt;
        }
        if (cnt == n-1) ++ans;
    }
    cout << ans << '\n';

#ifdef LOCAL_DEFINE
#endif
    return 0;
}