Submission #171785

#	Time	Username	Problem	Language	Result	Execution time	Memory
171785		VEGAnn	Marriage questions (IZhO14_marriage)	C++14	66 / 100	1579 ms	12768 KiB

marriage

#include <bits/stdc++.h>
#define sz(x) ((int)x.size())
#define PB push_back
#define MP make_pair
#define ft first
#define sd second
#define pii pair<int, int>
#define pi3 pair<pii, int>
#define MP3(a,b,c) MP(MP(a, b), c)
using namespace std;
const int oo = 1e9;
const int N = 32000;
const int K = 110;
const int PW = 20;

struct edge{
    int x, y, cap, flow;

    edge(int _x, int _y, int _c, int _f): x(_x), y(_y), cap(_c), flow(_f) {}
};

vector<edge> edges;
queue<int> q;
vector<int> g[N];
int ans = 0, s, t, n, m, k, dst[N], ptr[N];

void add_edge(int x, int y, int cap){

    g[x].PB(sz(edges));
    edges.PB(edge(x, y, cap, 0));

    g[y].PB(sz(edges));
    edges.PB(edge(y, x, 0, 0));

}

bool bad(int l, int r, int v){
    if (v == s || v == t || v < m) return 0;
    return !(m + l <= v && v <= m + r);
}

bool bfs(int l, int r){
    fill(dst, dst + t + 1, oo);

    dst[s] = 0;
    while (sz(q)) q.pop();
    q.push(s);

    while (sz(q)){
        int v = q.front(); q.pop();

        for (int nm : g[v]){
            edge u = edges[nm];
            if (!bad(l, r, u.y) && u.cap > u.flow && dst[u.y] > dst[v] + 1){
                dst[u.y] = dst[v] + 1;
                q.push(u.y);
            }
        }
    }

    return (dst[t] < oo);
}

int dfs(int v, int pshd){
    if (pshd == 0) return 0;
    if (v == t) return pshd;
    for (; ptr[v] < sz(g[v]); ptr[v]++){
        int nm = g[v][ptr[v]];
        edge u = edges[nm];
        if (dst[u.y] != dst[v] + 1) continue;
        int nw = dfs(u.y, min(pshd, u.cap - u.flow));
        if (nw){
            edges[nm].flow += nw;
            edges[nm ^ 1].flow -= nw;
            return nw;
        }
    }
    return 0;
}

bool ok(int l, int r){

    for (int it = 0; it < sz(edges); it += 2){
        edge u = edges[it];
        if (bad(l, r, u.x) || bad(l, r, u.y)) continue;
        edges[it].flow = 0;
        edges[it ^ 1].flow = 0;
    }

    int flow = 0;

    while (bfs(l, r)){
        fill(ptr, ptr + t + 1, 0);
        int pshd = dfs(s, oo);
        while (pshd > 0){
            flow += pshd;
            pshd = dfs(s, oo);
        }
    }

    return (flow == m);
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);

    cin >> n >> m >> k;

    for (int i = 0; i < k; i++){
        int x, y; cin >> y >> x;
        x--; y--;
        add_edge(x, m + y, 1);
    }

    s = n + m;
    t = n + m + 1;

    for (int i = 0; i < m; i++)
        add_edge(s, i, 1);

    for (int i = 0; i < n; i++)
        add_edge(i + m, t, 1);

    for (int l = 0, r = 0; l < n; l++){
        while (r < n && !ok(l, r))
            r++;
        if (r >= n) break;
        ans += n - r;
    }

    cout << ans;

    return 0;
}

• Subtask 1: 66 / 100