自由线段树

分情况讨论找规律

#include<bitsstdc++.h>
#define ll long long
#define maxn 1000005
using namespace std;
struct nod{
	int l,r,v;
	nod(){}
	nod(int a,int b,int c) {l=a; r=b; v=c;}
};
int n,q;
int num[505][505];
ll dp[505][505];
vector<nod> now;
ll dfs(int l,int r){
	if (dp[l][r]!=-1) return dp[l][r];
	if (l==r) return dp[l][r]=0; 
	dp[l][r]=1ll<<60;
	for (int k=l;k<r;k++) 
	{
		ll cost=0;	
		// for (nod tt:now)
        for (vector<nod>::iterator tt = now.begin(); tt < now.end(); tt++)
			if (max((*tt).l,l)<=min((*tt).r,r)) 
			{
				if (!((*tt).l<=l && r<=(*tt).r))
					if ((*tt).l<=k && k+1<=(*tt).r) cost+=(*tt).v;
			}
		dp[l][r]=min(dp[l][r],dfs(l,k)+dfs(k+1,r)+cost);
	}
	return dp[l][r];
}
int main(){
	memset(dp,-1,sizeof(dp));
	cin>>n>>q;
	int l,r;
	for (int i=1;i<=q;i++) {cin>>l>>r; num[l][r]++;}
	for (int l=1;l<=n;l++) 
        for (int r=l;r<=n;r++) 
            if (num[l][r]) 
                now.push_back(nod(l,r,num[l][r]));
	cout<<dfs(1,n)+q<<endl;
}