BZOJ 2959 长跑

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LCT+缩边双＋并查集

　显然如果进入一个边双联通分量，那一定能取遍所有点再出来．于是只要维护边双即可．对于加边，需要缩点，用LCT即可，判断是不是在一个边双里用个并查集就行．

　此题时限比较紧．注意到在缩点之后，LCT上的操基本只有access需要查询真实父亲（因为缩点之后的点单独属于一个分量），其他操作并不需要查并查集．把这个优化掉就能过了．．．？

#include<cstdio>#include<algorithm>#define N 150005#define IL inlineusing namespace std;namespace IO {    char _B[1 << 26], *_S = _B;    #define Begin() fread(_B, 1, 1 << 26, stdin)    #define inline __inline__ __attribute__((always_inline))    inline int read() {        register int x, b;        for ( ; *_S < '-'; ++ _S);        for (*_S != '-' ? x = *_S ++ - '0', b = 1 : (_S ++, x = b = 0);        *_S >= '0'; x = (x << 3) + (x << 1) + *_S ++ - '0');        return b ? x : -x;    }}namespace runzhe2000{    using namespace IO;    int n, m, val[N];    struct UFS    {        int f[N];        int find(int x){return x == f[x] ? x : f[x] = find(f[x]);}        inline void unio(int x, int y){f[find(x)] = find(y);}    }s, st;    struct node *tot, *null, *pos[N], *fir;    struct node    {        node *ch[2], *fa; int sum, val, rev;        IL node* F(){return pos[s.find(this - fir)];}        IL node* Fa(){return fa->F() == F() ? null : fa->F();}    }mem[N], *_t;    node *newnode(int v)    {        node *p = ++tot; *p = *null;        p->val = p->sum = v;        return p;    }    void init()    {        pos[0] = null = tot = fir = mem;        null->ch[0] = null->ch[1] = null->fa = null;        null->sum = null->val = null->rev = 0;    }    int type(node *p){return p->fa->ch[1]==p;}    bool isroot(node *p){return p != p->fa->ch[type(p)];}    void pushup(node *p){p->sum = p->val + p->ch[0]->sum + p->ch[1]->sum;}    void pushdown(node *p)    {        if(p->rev)        {            _t = p->ch[0], p->ch[0] = p->ch[1], p->ch[1] = _t;            p->ch[0] = p->ch[0], p->ch[1] = p->ch[1];            p->ch[0]->rev ^= 1, p->ch[1]->rev ^= 1, p->rev = 0;        }    }    void pre(node *p){if(!isroot(p)) pre(p->Fa()); pushdown(p);}    void rotate(node *p)    {        node *f = p->fa; int d = type(p);        (p->fa = f->fa), !isroot(f) ? p->fa->ch[type(f)] = p : 0;        (f->ch[d] = p->ch[!d]) != null ? p->ch[!d]->fa = f : 0;        p->ch[!d] = f, f->fa = p; pushup(f);    }       IL void splay(node *p)    {        for(pre(p); !isroot(p);)        {            node *f = p->fa;            if(isroot(f)) rotate(p);            else {if(type(p) == type(f)) rotate(f); else rotate(p); rotate(p);}        }         pushup(p);    }    IL void access(node *p)    {        node *tmp = null;        for(; p != null; p = (tmp = p)->fa)        {            splay(p);            p->ch[1] = tmp;            p->fa = p->Fa();            pushup(p);        }    }    IL void makeroot(node *p)    {        access(p);        splay(p);        p->rev ^= 1;    }    IL void link(node *a, node *b)    {        makeroot(a);        a->fa = b;    }    void reduc(node *a, node *b)    {        if(a == null) return;        s.unio(a - mem, b - mem);        b->val += a->val;        reduc(a->ch[0], b);        reduc(a->ch[1], b);        a->ch[0] = a->ch[1] = null;    }    IL void main()    {        int happy = Begin();        n = read(); m = read();         init();        for(int i = 1, v; i <= n; i++)        {            s.f[i] = i, st.f[i] = i;            pos[i] = newnode(val[i] = read());        }        int op, A, B;        node *pA, *pB;        for(int i = 1; i <= m; i++)        {            op = read(), A = read(), B = read();            pA = pos[A]->F(), pB = pos[B]->F();            if(op == 1)            {                if(st.find(A) != st.find(B))link(pA, pB), st.unio(A, B);                else                {                    int fA = s.find(A), fB = s.find(B);                    if(fA != fB)                    {                        makeroot(pA);                        access(pB);                        splay(pB);                        reduc(pB->ch[0]->F(), pB);                        pushup(pB);                    }                }            }            else if(op == 2)            {                splay(pA);                pA->val += B - val[A];                pushup(pA);                val[A] = B;            }            else            {                if(st.find(A) != st.find(B)) puts("-1");                else                {                    makeroot(pA);                    access(pB);                    splay(pB);                    printf("%d\n",pB->sum);                }            }        }    }}int main(){    runzhe2000::main();}

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