模板库

完善中……

优化

快读快输

inline int read(){
	int t=0,f=1;
	char ch=getchar();
	while(ch<'0'||ch>'9') {
		if(ch=='-') f=-f;
		ch=getchar();
	}
	while(ch>='0'&&ch<='9') {
		t=t*10+ch-'0';
		ch=getchar();
	}
	return t*f;
}
void write(int x){
    if(x<0) {putchar('-');x=-x;}
    if(x>9) write(x/10);
    putchar(x%10+'0');
}

组合计数

逆元预处理

	lx[0]=1;lx[1]=1;
	for(int i=2;i<N;i++) lx[i]=lx[i-1]*i%mod;
	inv[N-1]=ksm(lx[N-1],mod-2);
	for(int i=N-2;i>=0;i--) inv[i]=(inv[i+1])*(i+1)%mod;

快速幂

int ksm(int x,int y) {int t=1;while(y){if(y&1)t=t*x%mod;x=x*x%mod;y>>=1;}return t;}

组合数

int C(int x,int y) {if(x<y) return 0;return lx[x]*inv[y]%mod*inv[x-y]%mod;}

lucas

int lucas(int x,int y) {
	if(x<mod&&y<mod) return C[x][y];
	return lucas(x%mod,y%mod)*lucas(x/mod,y/mod)%mod;
}

exgcd

void exgcd(int a,int b) {
	if(b==0) {
		y=0;x=1;return ;
	}
	exgcd(b,a%b);
	tmp=x;
	x=y;
	y=tmp-y*(a/b);
}

数据结构

树状数组

#define int long long 
#define lowbit(x) (x&(-x))
void add(int x,int y) {if(x==0) return ;while(x<N) {c[x]+=y;x+=lowbit(x);};}
int ask(int x) {int t=0;while(x) {t+=c[x];x-=lowbit(x);}return t;}

线段树

真是好标准一颗线段树，感觉自己已经很久没有写过build()了。

struct stu {
	int maxx,minn,add;
	friend stu operator +(stu a,stu b) {
		a.minn=min(a.minn,b.minn);
		a.maxx=max(a.maxx,b.maxx);
		return a;
	}
}t[N*4];
int read() {int x;cin>>x;return x;}
void spread(int p) {
	if(t[p].add) {
		t[p*2].add+=t[p].add;
		t[p*2+1].add+=t[p].add;
		t[p*2].minn+=t[p].add;
		t[p*2+1].minn+=t[p].add;
		t[p*2].maxx+=t[p].add;
		t[p*2+1].maxx+=t[p].add;
		t[p].add=0;
	}
}
void change(int p,int l,int r,int tl,int tr,int k) {
	if(tl<=l&&r<=tr) {
		t[p].add+=k;
		t[p].maxx+=k;
		t[p].minn+=k;
		return ;
	}
	spread(p);
	int mid=(l+r)>>1;
	if(tl<=mid) change(p*2,l,mid,tl,tr,k);
	if(mid<tr) change(p*2+1,mid+1,r,tl,tr,k);
	t[p].minn=min(t[p*2].minn,t[p*2+1].minn);
	t[p].maxx=max(t[p*2].maxx,t[p*2+1].maxx);
}
stu ask(int p,int l,int r,int tl,int tr) {
	if(tr<tl) {
		return {-10000000,1000000000000,0};
	}
	if(tl<=l&&r<=tr) {
		// cerr<<"Ask "<<p<<" "<<t[p].minn<<" "<<t[p].maxx<<" "<<l<<" "<<r<<endl;
		return t[p];
	}
	spread(p);
	int mid=(l+r)>>1;
	stu ans; ans={0,0,0};
	ans.minn=1e18;ans.maxx=-1e18;
	if(tl<=mid) ans=ans+ask(p*2,l,mid,tl,tr);
	if(mid<tr) ans=ans+ask(p*2+1,mid+1,r,tl,tr);
	return ans;	
}
void build(int p,int l,int r) {
	t[p].add=0;t[p].minn=1e9;t[p].maxx=-1e9;
	if(l==r) {
		t[p].minn=t[p].maxx=min(l,n);
		// cerr<<"Build "<<p<<" "<<t[p].minn<<" "<<t[p].maxx<<endl;
		return ;
	}
	int mid=(l+r)>>1;
	build(p*2,l,mid);
	build(p*2+1,mid+1,r);
	t[p].minn=min(t[p*2].minn,t[p*2+1].minn);
	t[p].maxx=max(t[p*2].maxx,t[p*2+1].maxx);
}

字符串

KMP

	nxt[1]=0;
	for(int i=2,j=0;i<=m;i++) {
		while(j&&s[j+1]!=s[i]) {j=nxt[j];}
		if(s[j+1]==s[i]) {j++;}
		nxt[i]=j;
		if(nxt[i]==n) {cout<<i-n*2<<endl;}
	}

Hash

manacher

void manacher() {
	for(int r=0,mid=0,i=1;i<=tot;i++) {
		man[i]=(i<=r?min(man[mid*2-i],r-i+1):1);
		while(t[i+man[i]]==t[i-man[i]]) man[i]++;
		if(i+man[i]>r) {
			r=i+man[i]-1;
			mid=i;
		}
		if(man[i]>ans) ans=man[i];
	}
}

图论

差分约束

void spfa() {
	memset(dis,0x3f,sizeof(dis));
	queue<int>q;
	q.push(n+1);
	dis[n+1]=0;
	vis[n+1]=1;
	while(q.size()) {
		int x=q.front();q.pop();
		vis[x]=0;
		cnt[x]++;
		if(cnt[x]>=n) {
			cout<<"NO"<<endl;
			exit(0); 
		}
		for(auto y:e[x]) {
			if(dis[y.first]>dis[x]+y.second) {
				dis[y.first]=dis[x]+y.second;
				if(vis[y.first]==0) {
					vis[y.first]=1;
					q.push(y.first);
				}
			}
		}
	}
}
	for(int i=1;i<=m;i++) {
		int c1,c2,y;
		c1=read();c2=read();y=read();
		e[c2].push_back(make_pair(c1,y));
	}
	for(int i=1;i<=n;i++) {
		e[n+1].push_back(make_pair(i,0));
	}

Tarjan

边双

void tarjan(int x,int fa) {
	dfn[x]=low[x]=++tot;
	for(auto y:e[x]) {
		if(y.second==fa) continue;
		if(dfn[y.first]) {
			low[x]=min(low[x],dfn[y.first]);
		}
		else {
			tarjan(y.first,y.second);
			low[x]=min(low[x],low[y.first]);
			if(low[y.first]>dfn[x]) {
				bridge[y.second]=1;
			}
		}
	}
}
void dfs(int x,int fa) {
	vis[x]=1;
	o[cnt].push_back(x);
	for(auto y:e[x]) {
		if(bridge[y.second]) continue;
		if(vis[y.first]) continue;
		dfs(y.first,x);
	}
}