suoi46 最大和和 (线段树)

《Segment tree Beats!》，反正我不会

 #include<bits/stdc++.h>
 #define pa pair<int,int>
 #define CLR(a,x) memset(a,x,sizeof(a))
 using namespace std;
 typedef long long ll;
 const int maxn=4e5+;
 const ll inf=1e15+;

 inline ll rd(){
     ll x=;char c=getchar();int neg=;
     while(c<''||c>''){if(c=='-') neg=-;c=getchar();}
     while(c>=''&&c<='') x=x*+c-'',c=getchar();
     return x*neg;
 }

 ll a[maxn];
 int N,M;
 ll sum[maxn<<],mn[maxn<<][],se[maxn<<],laz[maxn<<];

 inline void update(int p){
     sum[p]=sum[p<<]+sum[p<<|];
     if(mn[p<<][]==mn[p<<|][]){
         mn[p][]=mn[p<<][],mn[p][]=mn[p<<][]+mn[p<<|][];
         se[p]=min(se[p<<],se[p<<|]);
     }
     else if(mn[p<<][]<mn[p<<|][]){
         mn[p][]=mn[p<<][],mn[p][]=mn[p<<][];
         se[p]=min(se[p<<],mn[p<<|][]);
     }
     else if(mn[p<<][]>mn[p<<|][]){
         mn[p][]=mn[p<<|][],mn[p][]=mn[p<<|][];
         se[p]=min(se[p<<|],mn[p<<][]);
     }
 }

 void pushdown(int p){
     if(!laz[p]) return;
     ll x=laz[p];laz[p]=;
     if(x<=mn[p][]) return;
     laz[p<<]=max(x,laz[p<<]);
     laz[p<<|]=max(x,laz[p<<|]);
     if(x<se[p]){
         sum[p]+=mn[p][]*(x-mn[p][]);
         mn[p][]=x;
         return;
     }
     pushdown(p<<);pushdown(p<<|);
     update(p);

 }

 void change(int p,int l,int r,int x,int y,ll z){
     if(x<=l&&r<=y){
         laz[p]=max(laz[p],z);
         pushdown(p);
     }
     else{
         pushdown(p);
         int m=l+r>>;
         if(x<=m) change(p<<,l,m,x,y,z);
         else pushdown(p<<);
         if(y>=m+) change(p<<|,m+,r,x,y,z);
         else pushdown(p<<|);
         update(p);
     }
 }

 void build(int p,int l,int r){
     if(l==r){
         mn[p][]=sum[p]=a[l];
         mn[p][]=,se[p]=inf;
     }else{
         int m=l+r>>;
         build(p<<,l,m);build(p<<|,m+,r);
         update(p);
     }
 }

 ll query(int p,int l,int r,int x,int y){
     pushdown(p);
     if(x<=l&&r<=y) return sum[p];
     int m=l+r>>;ll re=;
     if(x<=m) re=query(p<<,l,m,x,y);
     if(y>=m+) re+=query(p<<|,m+,r,x,y);
     return re;
 }

 int main(){
     //freopen("","r",stdin);
     int i;
     N=rd(),M=rd();
     for(i=;i<=N;i++)
         a[i]=rd();
     build(,,N);
     for(i=;i<=M;i++){
         ll a=rd(),b=rd(),c=rd();
         if(!a) printf("%lld\n",query(,,N,b,c));
         else change(,,N,b,c,a);
     }
     return ;
 }