Starry

发表于 更新于 分类于 本文字数： 296 阅读时长 ≈ 1 分钟

会了

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//2709 in fact 

#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

ll n,m,k,a[(int)5e4+9],fk,belong[(int)5e4+9],ans[(int)5e4+9],l=1,r,sum,cnt[(int)5e4+9];

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>n>>m>>k;
    for(int i=1;i<=n;++i)cin>>a[i];

    fk=ceil(n/sqrt(m));
    for(int i=1;i<=n;++i){
    	belong[i]=(i-1)/fk;
    }

    vector<array<int,3>> q;
    for(int i=1,x,y;i<=m;++i){
    	cin>>x>>y;
    	q.push_back({x,y,i});
    }
    sort(q.begin(),q.end(),[](const array<int,3>& aa,const array<int,3>& bb){return belong[aa[0]]==belong[bb[0]]?aa[1]<bb[1]:belong[aa[0]]<belong[bb[0]];});

    for(auto &&[aa,bb,cc]:q){
    	while(l<aa)sum-=2ll*cnt[a[l]]-1ll,cnt[a[l]]-=1,l+=1;
    	while(l>aa)l-=1,sum+=2ll*cnt[a[l]]+1ll,cnt[a[l]]+=1;
    	while(r<bb)r+=1,sum+=2ll*cnt[a[r]]+1ll,cnt[a[r]]+=1;
    	while(r>bb)sum-=2ll*cnt[a[r]]-1ll,cnt[a[r]]-=1,r-=1;
    	ans[cc]=sum;
    }
    for(int i=1;i<=m;++i)cout<<ans[i]<<"\n";
    return 0;
}

发表于 更新于 分类于 本文字数： 524 阅读时长 ≈ 2 分钟

注意图不一定联通

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#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

struct dsu{
	vi fa,sz;
	dsu(int n){
		fa.resize(n+1),sz.resize(n+1);
		for(int i=1;i<=n;++i)fa[i]=i,sz[i]=1;
	}
	int fnd(int x){
		return fa[x]==x?x:fa[x]=fnd(fa[x]);
	}
	bool merge(int x ,int y){
		int oa=fnd(x),ob=fnd(y);
		if(oa!=ob){
			fa[ob]=oa,sz[oa]+=sz[ob];
			return true;
		}
		return false;
	}
};

int n,m,q,hd[(int)1e5+9],tot=1,lg[(int)1e5+9],d[(int)1e5+9],fa[(int)1e5+9][21],dp[(int)1e5+9][21]; 
struct Edge{
	int to,nxt,w;
}e[(int)1e6+9];

void add(int u,int v,int w){
	e[++tot]={v,hd[u],w},hd[u]=tot;
	e[++tot]={u,hd[v],w},hd[v]=tot;
}

void dfs(int u,int pre,int lst){
	fa[u][0]=pre,d[u]=d[pre]+1,dp[u][0]=lst;
	for(int i=1;i<=lg[d[u]];++i)fa[u][i]=fa[fa[u][i-1]][i-1],dp[u][i]=max({dp[u][i-1],dp[fa[u][i-1]][i-1]});
	for(int eg=hd[u];eg;eg=e[eg].nxt)if(e[eg].to!=pre)dfs(e[eg].to,u,e[eg].w);
}


int LCA(int x,int y){
	int res=0;
	if(d[x]<d[y])swap(x,y);
	while(d[x]>d[y])res=max(res,dp[x][lg[d[x]-d[y]]]),x=fa[x][lg[d[x]-d[y]]];
	if(x==y)return res;
	for(int k=lg[d[x]];k>=0;--k)if(fa[x][k]!=fa[y][k])res=max({res,dp[x][k],dp[y][k]}),x=fa[x][k],y=fa[y][k];
	return max({dp[x][0],dp[y][0],res});
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    vector<array<int,3>>edge;
    cin>>n>>m;
    for(int i=2;i<=n;++i)lg[i]=lg[i>>1]+1;
    dsu d(n);

    for(int i=1,x,y,z;i<=m;++i){
    	cin>>x>>y>>z;
    	edge.push_back({x,y,z});
    }
    sort(all(edge),[](array<int,3> aa,array<int,3> bb){return aa[2]<bb[2];});
    for(auto [aa,bb,cc]:edge)if(d.merge(aa,bb))add(aa,bb,cc);
    for(int i=1;i<=n;++i)if(d.fnd(i)==i)dfs(i,0,0);
	
	cin>>q;
	for(int i=1,x,y;i<=q;++i){
		cin>>x>>y;
		if(d.fnd(x)!=d.fnd(y))cout<<"impossible\n";
		else cout<<LCA(x,y)<<"\n";
	}
    return 0;
}

发表于 更新于 分类于 本文字数： 295 阅读时长 ≈ 1 分钟

LCA板子题

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#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

ll n,m,s,fa[500009][21],d[500009],lg[500009];
vi g[500009]; 

void dfs(int u,int pre,int dep){
	fa[u][0]=pre,d[u]=dep;
	for(int i=1;i<=lg[d[u]];++i)fa[u][i]=fa[fa[u][i-1]][i-1];
	for(auto it:g[u])if(it!=pre)dfs(it,u,dep+1);
}

int LCA(int x,int y){
	if(d[x]<d[y])swap(x,y);
	while(d[x]>d[y])x=fa[x][lg[d[x]-d[y]]];
	if(x==y)return x;
	for(int k=lg[d[x]];k>=0;--k)if(fa[x][k]!=fa[y][k])x=fa[x][k],y=fa[y][k];
	return fa[x][0];
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>n>>m>>s;
	for(int i=2;i<=n;++i)lg[i]=lg[i>>1]+1;

    for(int i=1,x,y;i<n;++i){
    	cin>>x>>y;
    	g[x].push_back(y),g[y].push_back(x);
    }
    dfs(s,0,1);
    for(int i=1,x,y;i<=m;++i){
    	cin>>x>>y;
    	cout<<LCA(x,y)<<"\n";
    }

    return 0;
}

发表于 更新于 分类于 本文字数： 556 阅读时长 ≈ 2 分钟

想起还有道CF计数题没补…

题意是求，jls的取模整数板子好像有些问题。

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#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x & (-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;

using ll = long long;
// assume -P <= x < 2P
const int P = 998244353, mod = P;

int powmod(int a, int b)
{
    int res = 1;
    for (; b > 0; b >>= 1, a = 1ll * a * a % mod)
        if (b & 1)
            res = 1ll * res * a % mod;
    return res;
}

template <int MOD, int RT>
struct mint
{
    static const int mod = MOD;
    static constexpr mint rt() { return RT; } // primitive root for FFT
    int v;
    explicit operator int() const { return v; } // explicit -> don't silently convert to int
    mint() : v(0) {}
    mint(ll _v)
    {
        v = int((-MOD < _v && _v < MOD) ? _v : _v % MOD);
        if (v < 0)
            v += MOD;
    }
    bool operator==(const mint &o) const
    {
        return v == o.v;
    }
    friend bool operator!=(const mint &a, const mint &b)
    {
        return !(a == b);
    }
    friend bool operator<(const mint &a, const mint &b)
    {
        return a.v < b.v;
    }

    mint &operator+=(const mint &o)
    {
        if ((v += o.v) >= MOD)
            v -= MOD;
        return *this;
    }
    mint &operator-=(const mint &o)
    {
        if ((v -= o.v) < 0)
            v += MOD;
        return *this;
    }
    mint &operator*=(const mint &o)
    {
        v = int((ll)v * o.v % MOD);
        return *this;
    }
    mint &operator/=(const mint &o) { return (*this) *= inv(o); }
    friend mint pow(mint a, ll p)
    {
        mint ans = 1;
        assert(p >= 0);
        for (; p; p /= 2, a *= a)
            if (p & 1)
                ans *= a;
        return ans;
    }
    friend mint inv(const mint &a)
    {
        assert(a.v != 0);
        return pow(a, MOD - 2);
    }

    mint operator-() const { return mint(-v); }
    mint &operator++() { return *this += 1; }
    mint &operator--() { return *this -= 1; }
    friend mint operator+(mint a, const mint &b) { return a += b; }
    friend mint operator-(mint a, const mint &b) { return a -= b; }
    friend mint operator*(mint a, const mint &b) { return a *= b; }
    friend mint operator/(mint a, const mint &b) { return a /= b; }
};

using Z = mint<mod, 3>;
Z inv2;
Z cal(ll n)
{
    Z ans = Z(n)*Z(n+1)*inv2*61;
    for (int i = 0; i < 61; ++i)
    {
        ll bs = 1ll << (i + 1);
        ll cnt = n / bs;
        Z qsb = 0;
        if(cnt){
            qsb += Z(cnt) * Z(bs * (cnt - 1)) * Z((1ll<<i)) * inv2;
            qsb += Z(cnt) * Z(1ll<<i) * Z((1ll<<i)-1) * inv2;
        }
        ll nxt=n;
        if (n & (1ll << i))nxt=nxt/(1ll << i)*((1ll << i))-1ll;

        {
            Z fr = nxt / bs * bs;
            Z bkcn =( nxt & ((1ll<<i) - 1)) + 1ll;
            //cerr<<fr<<"::"<<(nxt & ((1ll<<i) - 1))<<"\n";
            qsb += (bkcn) * Z(fr);
            qsb += (bkcn) * (bkcn - 1) * inv2;
        }

        ans -= qsb;
    }
    return ans;
}
ll tt, n;
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    inv2=inv(Z(2));
    cin >> tt;
    f(sb, 1, tt)
    {
        cin >> n;
        cout << (cal(n)).v << "\n";
    }
    return 0;
}

发表于 更新于 分类于 本文字数： 324 阅读时长 ≈ 1 分钟

题目链接

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#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x & (-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;

using ll = long long;

ll n, m, ans[(int)1e5 + 9], c[(int)1e5 + 9], cnt[(int)1e5 + 9], sz[(int)1e5 + 9], son[(int)1e5 + 9], res;
vector<int> g[(int)1e5 + 9];

void dfs(int u, int fa)
{
    for (auto it : g[u])
    {
        if (it != fa)
        {
            dfs(it, u), sz[u] += sz[it], son[u] = sz[son[u]] < sz[it] ? it : son[u];
        }
    }
    sz[u] += 1;
}

void cal(int u, int fa, int val, int bson)
{
    cnt[c[u]] += val;
    if (val == 1)
        res += cnt[c[u]] == 1;
    else
        res -= cnt[c[u]] == 0;
    for (auto it : g[u])
        if (it != fa && it != bson)
            cal(it, u, val, bson);
}

void dfs2(int u, int fa, int opt)
{
    for (auto it : g[u])
    {
        if (it != son[u] && it != fa)
        {
            dfs2(it, u, 1);
        }
    }
    if (son[u])
        dfs2(son[u], u, 0);
    cal(u, fa, 1, son[u]);
    ans[u] = res;
    if (opt)
        cal(u, fa, -1, 0);
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n;
    for (int i = 1, x, y; i < n; ++i)
    {
        cin >> x >> y;
        g[x].push_back(y), g[y].push_back(x);
    }
    f(i, 1, n) cin >> c[i];
    dfs(1, 0);
    dfs2(1, 0, 0);
    cin >> m;
    for (int i = 1, x; i <= m; ++i)
    {
        cin >> x;
        cout << ans[x] << "\n";
    }
    return 0;
}
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