「2017 山东一轮集训 Day4」棋盘(费用流）

棋盘模型 + 动态加边
#include<cstdio>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#define ll long long 
#define M 51
#define N 500010
#define mmp make_pair
const int inf = 0x3e3e3e3e;
using namespace std;
int read()
{
    int nm = 0, f = 1;
    char c = getchar();
    for(; !isdigit(c); c = getchar()) if(c == '-') f = -1;
    for(; isdigit(c); c = getchar()) nm = nm * 10 + c - '0';
    return nm * f;
}
char S[M][M];
struct Note
{
    int ver, nxt, vi, vj, cap, flow;
}edge[N];
int head[N], cnt = 1, n, s, t, cost, ans;
bool vis[5010];
int dis[5050], sd[5050 * 30], sum[5050 * 30], noteans[5050], upup;
int tota, totb, notea[M][M], noteb[M][M], suma[M * M], sumb[M * M], nowa[M * M], nowb[M * M];
void push(int vi, int vj, int flo, int ver)
{
//  cout << vi << " " << vj << " " << ver << "\n";
    cnt++; edge[cnt].vi = vi, edge[cnt].ver = ver, edge[cnt].vj = vj, edge[cnt].nxt = head[vi], head[vi] = cnt, edge[cnt].cap = flo;
    cnt++; edge[cnt].vi = vj, edge[cnt].ver = -ver, edge[cnt].vj = vi, edge[cnt].nxt = head[vj], head[vj] = cnt;
}

bool spfa(int be, int ed)
{
    queue<int> q;
    for(int i = 0; i <= t; i++) vis[i] = 0, dis[i] = inf;
    dis[be] = 0, sum[s] = 0x3e3e3e3e;
    q.push(be);
    while(!q.empty())
    {
        int now = q.front();
        q.pop();
        vis[now] = false;
        for(int i = head[now]; i; i = edge[i].nxt)
        {
            int vj = edge[i].vj;
            if(edge[i].flow >= edge[i].cap) continue;
            if(dis[vj] > dis[now] + edge[i].ver)
            {
                dis[vj] = dis[now] + edge[i].ver;
                sd[vj] = i;
                sum[vj] = min(sum[now], edge[i].cap - edge[i].flow);
                if(!vis[vj])
                {
                    vis[vj] = true;
                    q.push(vj);
                }
            }
        }
    }
    if(dis[ed] == inf) return 0;
    ans += sum[ed];
    cost += sum[ed] * dis[ed];
    int u = ed, x;
    while(u != be)
    {
        x = sd[u];
        int vi = edge[x].vi, vj = edge[x].vj;
        if(vi == s && nowa[vj] + 1< suma[vj])
        {
            nowa[vj]++;
            push(s, vj, 1, nowa[vj]);
        }
        if(vj == t &&  nowb[vi - tota] + 1 < sumb[vi - tota])
        {
            nowb[vi - tota]++;
            push(vi, t, 1, nowb[vi - tota]);
        }
        edge[x].flow += sum[ed];
        edge[x ^ 1].flow -= sum[ed];
        u = edge[x].vi;
    }
    return true;
}
int main()
{
    n = read();
    for(int i = 1; i <= n; i++) scanf("%s", S[i] + 1); 
    for(int i = 1; i <= n; i++)
    {
        for(int j = 1; j <= n; j++)
        {
            if(S[i][j] == '.') upup++;
        }
    }
    for(int i = 1; i <= n; i ++)
    {
        for(int j = 1; j <= n; j++)
        {
            if(j == 1 || (S[i][j - 1] == '#' && S[i][j] == '.')) tota++;
            if(S[i][j] == '#') continue;
            suma[tota]++, notea[i][j] = tota; 
        }
    }
    for(int j = 1; j <= n; j++)
    {
        for(int i = 1; i <= n; i++)
        {
            if(i == 1 || (S[i - 1][j] == '#' && S[i][j] == '.')) totb++;
            if(S[i][j] == '#') continue;
            sumb[totb]++, noteb[i][j] = totb;
            push(notea[i][j], tota + noteb[i][j], 1, 0);
        }
    }
    s = tota + totb + 1, t = s + 1;
    for(int i = 1; i <= tota; i++) if(suma[i]) push(s, i, 1, 0);
    for(int i = 1; i <= totb; i++) if(sumb[i]) push(i + tota, t, 1, 0);
    for(int tim = 1; tim <= upup; tim++)
    {
        spfa(s, t);
        noteans[tim] = cost;
    }
    int t = read();
    while(t--)
    {
        int x = read();
        if(x > upup) puts("0");
        else cout << noteans[x] << "\n";
    }
    return 0;
}
/*
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*/