讲解详见ppt%%%%
代码
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
typedef long long ll;
const int N=3e5+10;
const int M=2e6+10;
int n,m,cnt,d[N],f[N],rt[N];
ll len[N],sum;
struct P{;
int lc,rc;ll dis,v;
}q[M];
char cc;
inline