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  • Codeforces 696E ...Wait for it...(树链剖分)

    题目链接  ...Wait for it...

    考虑树链剖分。

    对于树上的每个点开一个set,记录当前该节点上所有的girls。

    每个节点初始的权值为set中的最小值。

    询问的时候每次在路径上寻找最小值,并返回这个点的编号。

    然后把这个点的set的第一个元素取出,换成下一个元素。

    因为女孩总数不超过1e5,所以总查询次数不会超过1e5

    修改操作用lazy标记就可以了。

    #include <bits/stdc++.h>
    
    using namespace std;
    
    #define rep(i, a, b)	for (int i(a); i <= (b); ++i)
    #define dec(i, a, b)	for (int i(a); i >= (b); --i)
    #define lson		i << 1, L, mid
    #define rson		i << 1 | 1, mid + 1, R
    #define ls		i << 1
    #define rs		i << 1 | 1
    #define MP		make_pair
    #define fi		first
    #define se		second
    
    
    typedef long long LL;
    typedef pair <LL, int> PII;
    
    const int N  = 1e5 + 10;
    const LL inf = 1e18;
    
    int n, m, q;
    int id, cnt = 0;
    int ret[N];
    int at[N], sz[N], son[N], top[N], f[N], in[N], out[N], deep[N], father[N];
    vector <int> v[N];
    set <PII> s[N];
    LL lazy[N << 2];
    PII t[N << 2];
    
    void dfs(int x, int fa, int dep){
    	sz[x] = 1;
    	son[x] = 0;
    	father[x] = fa;
    	deep[x] = dep;
    	for (auto u : v[x]){
    		if (u == fa) continue;
    		dfs(u, x, dep + 1);
    		sz[x] += sz[u];
    		if (sz[son[x]] < sz[u]) son[x] = u;
    	}
    }
    
    void dfs2(int x, int tp){
    	top[x] = tp;
    	in[x] = f[x]  = ++id;
    	if (son[x]) dfs2(son[x], tp);
    	for (auto u : v[x]){
    		if (u == father[x] || u == son[x]) continue;
    		dfs2(u, u);
    	}
    	out[x] = id;
    }
    
    void pushup(int i){
    	t[i] = min(t[ls], t[rs]);
    }
    
    void pushdown(int i){
    	if (lazy[i]){
    		lazy[ls] += lazy[i];
    		lazy[rs] += lazy[i];
    		t[ls].fi += lazy[i];
    		t[rs].fi += lazy[i];
    		lazy[i] = 0;
    	}
    }
    
    void build(int i, int L, int R){
    	lazy[i] = 0;
    	if (L == R){
    		t[i] = *s[L].begin();
    		return;
    	}
    
    	int mid = (L + R) >> 1;
    	build(lson);
    	build(rson);
    	pushup(i);
    }
    
    void update(int i, int L , int R , int l, int r, LL val){
    	if (l <= L && R <= r){
    		lazy[i] += val;
    		t[i].fi += val;
    		return;
    	}
    	
    	pushdown(i);
    	int mid = (L + R) >> 1 ;
    	if (l <= mid) update(lson, l, r, val);
    	if (r > mid)  update(rson, l, r, val);
    	pushup(i);
    }
    
    void modify(int i, int L, int R, int x){
    	if (L == R){
    		s[L].erase(s[L].begin());
    		t[i] = *s[L].begin();
    		t[i].fi += lazy[i];
    		return;
    	}
    	pushdown(i);
    	int mid = (L + R) >> 1 ;
    	if (x <= mid) modify(lson, x) ;
    	else modify(rson, x);
    	pushup(i);
    }
    
    PII query(int i, int L, int R, int l, int r){
    	if (l <= L && R <= r) return t[i];
    	pushdown(i);
    	int mid = (L + R) >> 1 ;
    	if (r <= mid) return query(lson, l, r);
    	if (l >  mid) return query(rson, l, r);
    	return min(query(lson, l, r), query(rson, l, r));
    }
    
    int Query(int x, int y){
    	PII ans = PII(inf, 0);
    	while (top[x] ^ top[y]){
    		if (deep[top[x]] < deep[top[y]]) swap(x, y);
    		ans = min(ans, query(1, 1, n, f[top[x]], f[x]));
    		x = father[top[x]];
    	}
    	if (deep[x] > deep[y]) swap(x, y);
    	ans = min(ans, query(1, 1, n, f[x], f[y]));
    	return ans.se;
    }
    
    int main(){
    
    	scanf("%d%d%d", &n, &m, &q);
    	rep(i, 2, n){
    		int x, y;
    		scanf("%d%d", &x, &y);
    		v[x].push_back(y);
    		v[y].push_back(x);
    	}
    
    	dfs(1, 0, 0);
    	dfs2(1, 1);
    
    	rep(i, 1, n) s[i].insert(MP(inf, 0));
    	at[0] = N - 1;
    
    	rep(i, 1, m){
    		int x;
    		scanf("%d", &x);
    		at[i] = x;
    		s[f[x]].insert(MP(i, i));
    	}
    
    	build(1, 1, n);
    
    	while (q--){
    		int op, x, y, lim;
    		LL val;
    		scanf("%d", &op);
    		if (op == 2){
    			scanf("%d%lld", &x, &val);
    			update(1, 1, n, in[x], out[x], val);
    		}
    		else{
    			scanf("%d%d%d", &x, &y, &lim);
    			cnt = 0;
    			while (lim--){
    				int idx = Query(x, y);
    				if (idx == 0) break;
    				ret[++cnt] = idx;
    				modify(1, 1, n, f[at[idx]]);
    			}
    			printf("%d", cnt);
    			rep(i, 1, cnt) printf(" %d", ret[i]);
    			putchar(10);
    		}
    	}
    
    	return 0;
    }
    
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  • 原文地址:https://www.cnblogs.com/cxhscst2/p/7644420.html
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