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  • Bzoj3514: Codechef MARCH14 GERALD07加强版

    题面

    传送门

    Sol

    首先每次加入边的两个点不联通,那么联通块的个数就要减(1)
    那么考虑怎么做
    莫名想到(LCT)
    然后就不会了。。。
    (orz)题解
    维护一个每条边的数组,如果这个点加入后形成环,那么就把这个数组设为环内最先加入的边的编号,特判自环,然后替换这条边
    没有替换为(0)
    那么每次询问答案就是求([l, r])内该数组小于(l)的边的个数,答案为(n)-个数(自己(yy)一下就好)
    主席树来求这个东西
    代码很丑

    # include <bits/stdc++.h>
    # define IL inline
    # define RG register
    # define Fill(a, b) memset(a, b, sizeof(a))
    using namespace std;
    typedef long long ll;
    const int _(4e5 + 5);
    const int __(4e6 + 5);
    
    IL ll Input(){
    	RG ll x = 0, z = 1; RG char c = getchar();
    	for(; c < '0' || c > '9'; c = getchar()) z = c == '-' ? -1 : 1;
    	for(; c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
    	return x * z;
    }
    
    int n, m, k, type, rpl[_], fa[_], cnt, id[_];
    struct Edge{
    	int u, v;
    } edge[_];
    struct LCT{
    	# define ls ch[0][x]
    	# define rs ch[1][x]
    	
    	int ch[2][_], fa[_], mn[_], val[_], S[_], rev[_];
    
    	IL LCT(){
    		Fill(val, 127); Fill(mn, 127);
    	}
    	
    	IL bool Son(RG int x){
    		return ch[1][fa[x]] == x;
    	}
    
    	IL bool Isroot(RG int x){
    		return ch[0][fa[x]] != x && ch[1][fa[x]] != x;
    	}
    
    	IL void Update(RG int x){
    		mn[x] = min(val[x], min(mn[ls], mn[rs]));
    	}
    
    	IL void Reverse(RG int x){
    		if(!x) return;
    		swap(ls, rs); rev[x] ^= 1;
    	}
    
    	IL void Adjust(RG int x){
    		if(!rev[x]) return;
    		rev[x] = 0; Reverse(ls); Reverse(rs);
    	}
    	
    	IL void Rotate(RG int x){
    		RG int y = fa[x], z = fa[y], c = Son(x);
    		if(!Isroot(y)) ch[Son(y)][z] = x; fa[x] = z;
    		ch[c][y] = ch[!c][x]; fa[ch[c][y]] = y;
    		ch[!c][x] = y; fa[y] = x;
    		Update(y);
    	}
    
    	IL void Splay(RG int x){
    		S[S[0] = 1] = x;
    		for(RG int y = x; !Isroot(y); y = fa[y]) S[++S[0]] = fa[y];
    		while(S[0]) Adjust(S[S[0]--]);
    		for(RG int y = fa[x]; !Isroot(x); Rotate(x), y = fa[x])
    			if(!Isroot(y)) Son(x) ^ Son(y) ? Rotate(x) : Rotate(y);
    		Update(x);
    	}
    
    	IL void Access(RG int x){
    		for(RG int y = 0; x; y = x, x = fa[x]) Splay(x), ch[1][x] = y, Update(x);
    	}
    
    	IL void Makeroot(RG int x){
    		Access(x); Splay(x); Reverse(x);
    	}
    
    	IL void Link(RG int x, RG int y){
    		Makeroot(x); fa[x] = y;
    	}
    
    	IL void Split(RG int x, RG int y){
    		Makeroot(x); Access(y); Splay(y);
    	}
    
    	IL void Cut(RG int x, RG int y){
    		Split(x, y); fa[x] = ch[0][y] = 0; Update(y);
    	}
    	
    	# undef ls
    	# undef rs
    } T;
    
    struct Segment{
    	int ls[__], rs[__], size[__], rt[_], cnt;
    
    	IL void Modify(RG int &x, RG int l, RG int r, RG int v){
    		ls[++cnt] = ls[x]; rs[cnt] = rs[x]; size[cnt] = size[x] + 1; x = cnt;
    		if(l == r) return;
    		RG int mid = (l + r) >> 1;
    		if(v <= mid) Modify(ls[x], l, mid, v);
    		else Modify(rs[x], mid + 1, r, v);
    	}
    
    	IL int Query(RG int A, RG int B, RG int l, RG int r, RG int L, RG int R){
    		if(L <= l && R >= r) return size[A] - size[B];
    		RG int mid = (l + r) >> 1, ans = 0;
    		if(L <= mid) ans = Query(ls[A], ls[B], l, mid, L, R);
    		if(R > mid) ans += Query(rs[A], rs[B], mid + 1, r, L, R);
    		return ans;
    	}
    } HJT;
    
    IL int Find(RG int x){  return x == fa[x] ? x : fa[x] = Find(fa[x]);  }
    
    int main(RG int argc, RG char* argv[]){
    	cnt = n = Input(); m = Input(); k = Input(); type = Input();
    	for(RG int i = 1; i <= n; ++i) fa[i] = i;
    	for(RG int i = 1; i <= m; ++i){
    		edge[i].u = Input(); edge[i].v = Input();
    		if(edge[i].u == edge[i].v){
    			rpl[i] = i;
    			continue;
    		}
    		RG int fx = Find(edge[i].u), fy = Find(edge[i].v);
    		if(fx != fy){
    			T.val[++cnt] = i; id[i] = cnt;
    			T.Link(cnt, edge[i].u), T.Link(cnt, edge[i].v);
    			fa[fx] = fy;
    		}
    		else{
    			T.Split(edge[i].u, edge[i].v);
    			rpl[i] = T.mn[edge[i].v];
    			T.Cut(id[rpl[i]], edge[rpl[i]].u); T.Cut(id[rpl[i]], edge[rpl[i]].v);
    			T.val[++cnt] = i; id[i] = cnt;
    			T.Link(cnt, edge[i].u), T.Link(cnt, edge[i].v);
    		}
    	}
    	for(RG int i = 1; i <= m; ++i){
    		HJT.rt[i] = HJT.rt[i - 1];
    		HJT.Modify(HJT.rt[i], 0, m, rpl[i]);
    	}
    	for(RG int ans = 0, i = 1; i <= k; ++i){
    		RG int l = Input(), r = Input();
    		if(type) l ^= ans, r ^= ans;
    		printf("%d
    ", ans = n - HJT.Query(HJT.rt[r], HJT.rt[l - 1], 0, m, 0, l - 1));
    	}
    	return 0;
    }
    
    
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  • 原文地址:https://www.cnblogs.com/cjoieryl/p/8372728.html
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