Submission #62417

#	Time	Username	Problem	Language	Result	Execution time	Memory
62417		Tenuun	Horses (IOI15_horses)	C++17	100 / 100	627 ms	43024 KiB

horses

#include<bits/stdc++.h>
#define mod 1000000007
#define ll long long

using namespace std;

int n, tr[2000000], id[500001];
ll bit[500001];
ll now=1;
vector<int>x, y;
set<int>a;

void update(int ind, int val){
	if(ind==0) return;
    while(ind<=500000){
        bit[ind]*=val;
        bit[ind]%=mod;
        ind+=ind&-ind;
    }
}

ll get(int ind){
    if(ind<0 || ind>n) return 1;
    ll ans=1;
    while(ind>0){
        ans*=bit[ind];
        ans%=mod;
        ind-=ind&-ind;
    }
    return ans;
}

void pre(){
    fill(bit, bit+500001, 1);
    a.insert(-1);
    a.insert(0);
    for(int i=0; i<n; i++){
        if(x[i]>1){
            a.insert(i);
            update(i+1, x[i]);
        }
    }
}

void build(int ind, int l, int r){
    if(l==r){
        tr[ind]=y[l];
        id[l]=ind;
        return;
    }
    build(ind*2, l, (l+r)/2);
    build(ind*2+1, (l+r)/2+1, r);
    tr[ind]=max(tr[ind*2], tr[ind*2+1]);
}

void upd(int ind){
    if(ind==0) return;
    tr[ind]=max(tr[ind*2], tr[ind*2+1]);
    upd(ind/2);
}

ll rmq(int ind, int l, int r, int L, int R){
    if(l==L && r==R) return tr[ind];
    int m=(l+r)/2;
    if(R<=m) return rmq(ind*2, l, m, L, R);
    else if(L>m) return rmq(ind*2+1, m+1, r, L, R);
    else{
        return max(rmq(ind*2, l, m, L, m), rmq(ind*2+1, m+1, r, m+1, R));
    }
}

ll find(){
	if(a.size()==1){
		return rmq(1, 0, n-1, 0, n-1);
	}
    ll ans=1, t=rmq(1, 0, n-1, *prev(a.end()), n-1);
    ll now=t;
    set<int>::iterator it;
    for(it=prev(a.end()); it!=a.begin() && now<mod; it--){
        if(now*x[*it]>mod) {
            break;
        }
        now*=x[*it];
    }
    ans=now%mod;
    now/=t;
    for(set<int>::iterator tmp=prev((prev(a.end()))); tmp!=prev(it) && tmp!=a.begin(); tmp--){
        now/=x[*next(tmp)];
        ans=max(ans, now*rmq(1, 0, n-1, *tmp, *next(tmp)-1));
    }
    ans%=mod;
    if(it!=a.begin()) {
    	ans*=get(*it+1);
    }
    ans%=mod;
    return ans;
}

int init(int N, int X[], int Y[]) {
    n=N;
    for(int i=0; i<n; i++) {x.push_back(X[i]); y.push_back(Y[i]);}
    pre();
    build(1, 0, n-1);
    return find();
}

ll pw(ll o, ll p){
    if(p==0) return 1;
    ll ans=pw(o, p/2);
    ans*=ans;
    ans%=mod;
    if(p%2) ans*=o;
    ans%=mod;
    return ans;
}

int updateX(int pos, int val){
    if(x[pos]==1 && val==1) return find();
    if(x[pos]>1 && val>1){
        update(pos+1, (val*pw(x[pos], mod-2)%mod));
        x[pos]=val;
        return find();
    }
    if(x[pos]==1){
        a.insert(pos);
        update(pos+1, val);
        x[pos]=val;
    }
    else{
        a.erase(a.find(pos));
        update(pos+1, pw(x[pos], mod-2));
        x[pos]=1;
    }
    return find();
}

int updateY(int pos, int val){
    tr[id[pos]]=val;
    upd(id[pos]/2);
    return find();
}

Compilation message (stderr)

horses.cpp: In function 'long long int find()':
horses.cpp:77:8: warning: declaration of 'now' shadows a global declaration [-Wshadow]
     ll now=t;
        ^~~
horses.cpp:9:4: note: shadowed declaration is here
 ll now=1;
    ^~~
horses.cpp: In function 'int init(int, int*, int*)':
horses.cpp:104:16: warning: conversion to 'int' from 'long long int' may alter its value [-Wconversion]
     return find();
            ~~~~^~
horses.cpp: In function 'int updateX(int, int)':
horses.cpp:118:40: warning: conversion to 'int' from 'long long int' may alter its value [-Wconversion]
     if(x[pos]==1 && val==1) return find();
                                    ~~~~^~
horses.cpp:120:45: warning: conversion to 'int' from 'long long int' may alter its value [-Wconversion]
         update(pos+1, (val*pw(x[pos], mod-2)%mod));
                       ~~~~~~~~~~~~~~~~~~~~~~^~~~~
horses.cpp:122:20: warning: conversion to 'int' from 'long long int' may alter its value [-Wconversion]
         return find();
                ~~~~^~
horses.cpp:131:25: warning: conversion to 'int' from 'long long int' may alter its value [-Wconversion]
         update(pos+1, pw(x[pos], mod-2));
                       ~~^~~~~~~~~~~~~~~
horses.cpp:134:16: warning: conversion to 'int' from 'long long int' may alter its value [-Wconversion]
     return find();
            ~~~~^~
horses.cpp: In function 'int updateY(int, int)':
horses.cpp:140:16: warning: conversion to 'int' from 'long long int' may alter its value [-Wconversion]
     return find();
            ~~~~^~

• Subtask 1: 17 / 17
• Subtask 2: 17 / 17
• Subtask 3: 20 / 20
• Subtask 4: 23 / 23
• Subtask 5: 23 / 23