4823: [Cqoi2017]老C的方块

很不争气地借用了别人家的题解。。

#include<iostream>#include<cstdio>#include<cstring>#include<vector>#include<queue>#include<algorithm>#include<cmath>#include<map>#define min(a,b) ((a) < (b) ? (a) : (b))using namespace std; const int INF = ~0U>>1;const int maxn = 2E5 + 20;const int maxm = 2E6 + 20; struct E{    int to,cap,flow; E(){}    E(int to,int cap,int flow): to(to),cap(cap),flow(flow){}}edgs[maxm]; struct Point{    int x,y; Point(){}    Point(int x,int y): x(x),y(y){}    bool operator < (const Point &B) const    {        if (x < B.x) return 1;        if (x > B.x) return 0;        return y < B.y;    }}p[maxn]; int C,R,n,m,s,t,cnt,tot,L[maxn],cur[maxn],w[maxn],A[maxn],B[maxn]; queue <int> Q;map <Point,int> M;vector <int> v[maxn]; inline int getint(){    char ch = getchar(); int ret = 0;    while (ch < '0' || '9' < ch) ch = getchar();    while ('0' <= ch && ch <= '9')        ret = ret * 10 + ch - '0',ch = getchar();    return ret;} inline void Add(int x,int y,int cap){    v[x].push_back(cnt); edgs[cnt++] = E(y,cap,0);    v[y].push_back(cnt); edgs[cnt++] = E(x,0,0);} void Build(){    for (int i = 1; i <= n; i++)    {        Add(A[i],B[i],w[i]);        if (p[i].x % 4 == 1 && !(p[i].y & 1))        {            Add(s,A[i],INF);            if (M.count(Point(p[i].x,p[i].y - 1)))                Add(B[i],A[M[Point(p[i].x,p[i].y - 1)]],w[i]);            if (M.count(Point(p[i].x,p[i].y + 1)))                Add(B[i],A[M[Point(p[i].x,p[i].y + 1)]],w[i]);            if (M.count(Point(p[i].x - 1,p[i].y)))                Add(B[i],A[M[Point(p[i].x - 1,p[i].y)]],w[i]);        }        else if (p[i].x % 4 == 0 && (p[i].y & 1))        {            Add(s,A[i],INF);            if (M.count(Point(p[i].x,p[i].y - 1)))                Add(B[i],A[M[Point(p[i].x,p[i].y - 1)]],w[i]);            if (M.count(Point(p[i].x,p[i].y + 1)))                Add(B[i],A[M[Point(p[i].x,p[i].y + 1)]],w[i]);            if (M.count(Point(p[i].x + 1,p[i].y)))                Add(B[i],A[M[Point(p[i].x + 1,p[i].y)]],w[i]);        }        else if (p[i].x % 4 == 1 && (p[i].y & 1))        {            if (M.count(Point(p[i].x + 1,p[i].y)))                Add(B[i],A[M[Point(p[i].x + 1,p[i].y)]],w[i]);        }        else if (p[i].x % 4 == 0 && !(p[i].y & 1))        {            if (M.count(Point(p[i].x - 1,p[i].y)))                Add(B[i],A[M[Point(p[i].x - 1,p[i].y)]],w[i]);        }        else if (p[i].x % 4 == 2 && (p[i].y & 1))        {            if (M.count(Point(p[i].x + 1,p[i].y)))                Add(B[i],A[M[Point(p[i].x + 1,p[i].y)]],w[i]);            if (M.count(Point(p[i].x,p[i].y - 1)))                Add(B[i],A[M[Point(p[i].x,p[i].y - 1)]],w[i]);            if (M.count(Point(p[i].x,p[i].y + 1)))                Add(B[i],A[M[Point(p[i].x,p[i].y + 1)]],w[i]);        }        else if (p[i].x % 4 == 3 && !(p[i].y & 1))        {            if (M.count(Point(p[i].x - 1,p[i].y)))                Add(B[i],A[M[Point(p[i].x - 1,p[i].y)]],w[i]);            if (M.count(Point(p[i].x,p[i].y - 1)))                Add(B[i],A[M[Point(p[i].x,p[i].y - 1)]],w[i]);            if (M.count(Point(p[i].x,p[i].y + 1)))                Add(B[i],A[M[Point(p[i].x,p[i].y + 1)]],w[i]);        }        else if ((p[i].x % 4 == 2 && !(p[i].y & 1)) || (p[i].x % 4 == 3 && (p[i].y & 1))) Add(B[i],t,w[i]);    }} inline bool BFS(){    for (int i = 1; i <= t; i++) L[i] = 0;    Q.push(s); L[s] = 1;    while (!Q.empty())    {        int k = Q.front(); Q.pop();        for (int i = 0; i < v[k].size(); i++)        {            E e = edgs[v[k][i]];            if (e.cap == e.flow || L[e.to]) continue;            L[e.to] = L[k] + 1; Q.push(e.to);        }    }    return L[t];} inline int Dinic(int x,int a){    if (x == t) return a; int flow = 0;    for (int &i = cur[x]; i < v[x].size(); i++)    {        E &e = edgs[v[x][i]];        if (e.cap == e.flow || L[e.to] != L[x] + 1) continue;        int f = Dinic(e.to,min(e.cap - e.flow,a));        if (!f) continue; flow += f; e.flow += f;        edgs[v[x][i]^1].flow -= f; a -= f;        if (!a) return flow;    }    if (!flow) L[x] = -1; return flow;} int main(){    #ifdef DMC        freopen("DMC.txt","r",stdin);    #endif         C = getint(); R = getint(); n = getint();    for (int i = 1; i <= n; i++)    {        int x = getint(),y;        y = getint(); w[i] = getint();        M[p[i] = Point(x,y)] = i;        A[i] = ++tot; B[i] = ++tot;    }         s = ++tot; t = ++tot;    Build(); int MinCut = 0;    while (BFS())    {        for (int i = 1; i <= t; i++) cur[i] = 0;        MinCut += Dinic(s,INF);    }    cout << MinCut << endl;    return 0;}