[OpenJudge] C15C Rabbit's Festival [PKU Campus 2015]

很久没有写过cdq分治了呢….

一个无向图,每一天都会有一些边白天消失,晚上复原
问每天白天连通点对数.
大致过程可以看下面这一小段伪代码

void Solve(int DayL,int DayR,int dep) {
    if (DayL == DayR) {
        Graph[dep].Union(DayL,DayR) ;
        ans[DayL] = Graph[dep].ans ;
    }
    int DayM = (DayL+Dayr)/2 ;
    Graph[dep+1] = Graph[dep] ;
    Graph[dep+1].Union(DayM+1,DayR) ;
    Solve(DayL,DayM,dep+1) ;
    Graph[dep+1] = Graph[dep] ;
    Graph[dep+1].Union(DayL,DayM) ;
    Solve(DayM+1,DayR,dep+1) ;
}

伪代码中的Union是指把那些时间区间里被删掉的边都添进来，也就是并查集的union，同时由旧图和添边记录一下新图的答案，传给下一层递归。
可以看到这样非常机智的省去了许多重新建图的麻烦。
群里有人说还要启发式并查集？反正没用就过了

/****************************************\
* Author : ztx
* Title  : PKU open 2015 C
* ALG    : cdq
* CMT    :
* Time   :
\****************************************/

#include <cstdio>
#define Rep(i,l,r) for(i=(l);i<=(r);i++)
#define rep(i,l,r) for(i=(l);i< (r);i++)
#define Rev(i,r,l) for(i=(r);i>=(l);i--)
#define rev(i,r,l) for(i=(r);i> (l);i--)
typedef long long ll ;
int CH , NEG ;
template <typename TP>inline void read(TP& ret) {
    ret = NEG = 0 ; while (CH=getchar() , CH<'!') ;
    if (CH == '-') NEG = true , CH = getchar() ;
    while (ret = ret*10+CH-'0' , CH=getchar() , CH>'!') ;
    if (NEG) ret = -ret ;
}
template <typename TP>inline void readc(TP& ret) {
    while (ret=getchar() , ret<'!') ;
    while (CH=getchar() , CH>'!') ;
}
template <typename TP>inline void reads(TP *ret) {
    ret[0]=0;while (CH=getchar() , CH<'!') ;
    while (ret[++ret[0]]=CH,CH=getchar(),CH>'!') ;
    ret[ret[0]+1]=0;
}

#include <cstring>
#include <vector>

#define  maxk  100010LL
#define  maxn  100010LL
#define  maxm  200010LL

int n , m , K ;

struct EDGE { int u,v,w; } ;
struct Graph {
    int n,m,fa[maxn],sz[maxn];
    EDGE e[maxm];
} G[17] ;

int fa[maxn] , sz[maxn] , pos[maxn] ;
ll ans[maxk] = {0} ;

inline int GetAnc(int u) { return fa[u] ? fa[u]=GetAnc(fa[u]) : u ; }

int i , u , v ;
inline void solve(int L,int R,int d) {
    if (L == R) {
        ans[L] = 0 ;
        Rep (i,1,G[d].n)
            ans[L] += (ll)G[d].sz[i]*(G[d].sz[i]-1)/2 ;
        return ;
    }
    Graph &g1 = G[d] ;
    Graph &g2 = G[d+1] ;
    int M = L+R>>1 ;
    Rep (i,1,g1.n) fa[i]=0, sz[i]=g1.sz[i] ;
    Rep (i,1,g1.m) if (g1.e[i].w > M) {
        u = GetAnc(g1.e[i].u) , v = GetAnc(g1.e[i].v) ;
        if (u != v) sz[u] += sz[v] , fa[v] = u ;
    }
    g2.n = g2.m = 0 ;
    Rep (i,1,g1.n) if (GetAnc(i)==i) {
        pos[i] = ++g2.n ;
        g2.fa[g2.n] = 0, g2.sz[g2.n] = sz[i] ;
    }
    Rep (i,1,g1.m) if (g1.e[i].w <= M) {
        u = pos[GetAnc(g1.e[i].u)] , v = pos[GetAnc(g1.e[i].v)] ;
        if (u != v)
            g2.e[++g2.m] = (EDGE){u,v,g1.e[i].w} ;
    }
    solve(L,M,d+1) ;
    Rep (i,1,g1.n) fa[i] = 0 , sz[i] = g1.sz[i] ;
    Rep (i,1,g1.m) if (g1.e[i].w <= M) {
        u = GetAnc(g1.e[i].u) , v = GetAnc(g1.e[i].v) ;
        if (u != v) sz[u] += sz[v] , fa[v] = u ;
    }
    g2.n = g2.m = 0 ;
    Rep (i,1,g1.n) if (GetAnc(i)==i) {
        pos[i] = ++g2.n ;
        g2.fa[g2.n] = 0 , g2.sz[g2.n] = sz[i] ;
    }
    Rep (i,1,g1.m) if (g1.e[i].w > M) {
        u = pos[GetAnc(g1.e[i].u)] , v = pos[GetAnc(g1.e[i].v)] ;
        if (u != v)
            g2.e[++g2.m] = (EDGE){u,v,g1.e[i].w} ;
    }
    solve(M+1,R,d+1) ;
}

int main() {
int i , u , v , w ;
//  #define READ
    #ifdef  READ
        freopen(".in" ,"r",stdin ) ;
        freopen(".out","w",stdout) ;
    #endif
    while (scanf("%d", &n)!=EOF) {
        read(m) , read(K) ;
        Rep (i,1,n) pos[i]=0;
        G[0].n = 0 , G[0].m = m ;
        Rep (i,1,m) {
            read(u),read(v),read(w) ;
            if (!pos[u]) pos[u] = ++G[0].n ;
            if (!pos[v]) pos[v] = ++G[0].n ;
            u = pos[u] , v = pos[v] ;
            G[0].e[i] = (EDGE){u,v,w} ;
        }
        Rep (i,1,G[0].n) G[0].fa[i] = 0 , G[0].sz[i] = 1 ;
        solve(1,K,0) ;
        Rep (i,1,K) printf("%lld\n", ans[i]) ;
    }
    #ifdef  READ
        fclose(stdin) ; fclose(stdout) ;
    #else
        getchar() ; getchar() ;
    #endif
    return 0 ;
}