一些模板

一些模板

归并排序

#include<iostream>
#include<cstdio>
const int N=5e5+100;
using namespace std;
int n,a[N],b[N];
long long num;
void msort(int l,int r)
{
	if (l==r) return ;
	int mid=(l+r)>>1;
	msort(l,mid);
	msort(mid+1,r);
	int i=l,j=mid+1,k=l;
	while (i<=mid&&j<=r)
	if (a[i]<=a[j]) b[k++]=a[i++];
	else
	{
		num=num+mid-i+1;    //  求逆序对
		b[k++]=a[j++];
	}
	while (i<=mid) b[k++]=a[i++];
	while (j<=r) b[k++]=a[j++];
	for (int i=l;i<=r;i++) a[i]=b[i];
	return ;
}
int main()
{
	scanf("%d",&n);
	for (int i=1;i<=n;i++)
	scanf("%d",a+i);
	msort(1,n);
	for (int i=1;i<=n;i++)
	printf("%d ",a[i]);
	printf("
");
	printf("%lld",num);     //输出逆序对
	return 0;
}

Matrix

#include<bits/stdc++.h>
#define ll long long
struct Mat{
	int size;
	ll **M=NULL;
	inline ll Start()
	{
		if (M!=NULL) return M[1][1];
		else return LLONG_MIN;
	}
	inline void Clear(int sz)
	{
		if (M==NULL) {New(sz);return ;}
		for (int i=0;i<=sz;i++)
		for (int j=0;j<=sz;j++)
		M[i][j]=0;
		return ;
	}
	inline void New(int sz)
	{
		if (M!=NULL)
		{
			printf("
This matrix has been used
");
			return ;
		}
		size=sz;
		M=new ll*[sz+10];
		for (int i=0;i<sz+10;i++)
		M[i]=new ll[sz+10];
		Clear(sz);
		return ;
	}
	inline void Build(int sz)
	{
		size=sz;
		if (M==NULL) New(sz);
		for (int i=1;i<=sz;i++) M[i][i]=1;
		return ;
	}
	inline void Init(ll now[],int sz)
	{
		if (M==NULL) New(sz);
		int num=0;
		for (int i=1;i<=sz;i++)
		for (int j=1;j<=sz;j++)
		M[i][j]=now[++num];
		return ;
	}
	inline void Out()
	{
		if (M!=NULL)
		for (int i=1;i<=size;i++)
		{
			for (int j=1;j<=size;j++)
			printf("%lld ",M[i][j]);
			printf("
");
		}
		return ;
	}
	inline void Delete()
	{
		for (int i=0;i<size+10;i++)
		delete []M[i] ;
		delete []M;
		M=NULL;
		size=0;
		return ;
	}
};
ll mod;
inline Mat operator * (Mat a,Mat b)
{
	Mat c;
	c.Clear(a.size);
	for (int i=1;i<=c.size;i++)
	for (int j=1;j<=c.size;j++)
	for (int k=1;k<=c.size;k++)
	c.M[i][j]=(c.M[i][j]+a.M[i][k]*b.M[k][j]%mod)%mod;
	return c;
}
inline Mat Mat_qpow(Mat a,ll p)
{
	Mat ans,base;
	base.New(a.size);
	ans.Build(a.size);
	for (base=a;p;p>>=1,base=base*base)
	if (p&1) ans=ans*base;
	return ans;	
}
int main()
{
	return 0;
}

网络流模板

#include<iostream>
#include<cstring>
#include<climits>
#include<cstdio>
#include<queue>
using namespace std;
const int N=1e4+100,M=1e5+100;
struct edge{
    int s,e,v,next;
}ed[(M<<1)];
queue<int>q;
int n,m,s,t,tot=1;
int head[N],deep[N],cur[N];
inline bool bfs(int s)
{
    memset(deep,0,sizeof(deep));
    for (int i=1;i<=n;i++)
    cur[i]=head[i];
    q.push(s);
    deep[s]=1;
    while (!q.empty())
    {
        int u=q.front();
        q.pop();
        for (int i=head[u];i;i=ed[i].next)
        {
            int to=ed[i].e;
            if (ed[i].v&&!deep[to])
            {
                deep[to]=deep[ed[i].s]+1;
                q.push(to);
            }
        }
    }
    return deep[t];
}
inline int dfs(int x,int flow)
{
    if (x==t) return flow;
    int out=0;
    for (int i=cur[x];i;i=ed[i].next)
    {
        cur[x]=i;
        int to=ed[i].e;
        if (ed[i].v&&deep[to]==deep[ed[i].s]+1)
        {
            int res=dfs(to,min(ed[i].v,flow));
            ed[i].v-=res;
            ed[i^1].v+=res;
            flow-=res;
            out+=res;
            if (!flow) break;
        }
    }
    if (!out) deep[x]=0;
    return out;
}
inline void add(int s,int e,int v)
{
    ed[++tot]=(edge){s,e,v,head[s]};
    head[s]=tot;
    return ;
}
int main()
{
    scanf("%d%d%d%d",&n,&m,&s,&t);
    for (int i=1;i<=m;i++)
    {
        int x,y,z;
        scanf("%d%d%d",&x,&y,&z);
        add(x,y,z);
        add(y,x,0);
    }
    int maxflow=0;
    while (bfs(s))
    maxflow+=dfs(s,INT_MAX);
    printf("%d
",maxflow);
    return 0;
}