Submission #981494

#	Time	Username	Problem	Language	Result	Execution time	Memory
981494		boyliguanhan	The Big Prize (IOI17_prize)	C++17	100 / 100	31 ms	2336 KiB

prize

//viewed solution
#include "prize.h"
#include<bits/stdc++.h>
using namespace std;
int unloli,ans=-1;
map<int,vector<int>> mem;
vector<int>ask2(int n){
    if(mem.count(n))
        return mem[n];
    return mem[n]=ask(n);
}
void calc(int l,int r,int tol,int tor){
    if(ans>=0)
        return;
    if(l>r)
        return;
    if(tol+tor==unloli)
        return;
    if(tol+tor+r-l+1==unloli){
        for(int i=l;i<=r;i++) {
            vector<int>x=ask2(i);
            if(x[0]+x[1]==0) {
                ans=i;
                return;
            }
        }
        return;
    }
    int mid=l+r>>1,pt=mid;
    vector<int>stuff=ask2(mid);
    if(stuff[0]+stuff[1]==0){
        ans=mid;
        return;
    }
    while(stuff[0]+stuff[1]-unloli&&pt>l){
        stuff=ask2(--pt);
        if(stuff[0]+stuff[1]==0){
            ans=pt;
            return;
        }
    }
    if(stuff[0]+stuff[1]==unloli)
        calc(mid+1,r,stuff[0],tor),
        calc(l,pt-1,tol,stuff[1]);
    else {
        stuff=ask2(++mid);
        if(stuff[0]+stuff[1]==0) {
            ans=mid;
            return;
        }
        while(stuff[0]+stuff[1]-unloli){
            stuff=ask2(++mid);
            if(stuff[0]+stuff[1]==0) {
                ans=mid;
                return;
            }
        }
        calc(mid+1,r,stuff[0],tor);
    }
}
int find_best(int n) {
    if(n<5002) {
        for(int i = 1; i < n; i++) {
            std::vector<int> res = ask2(i);
            if(res[0] + res[1] == 0)    
                return i;
        }
	    return 0;
    }
    map<int,int>cnt;
    int to=473;
    for(int i=0;i<to;i++){
        vector<int>x=ask2(i);
        if(x[0]+x[1]==0)
            return i;
        cnt[x[0]+x[1]]++;
        unloli=max(unloli,x[0]+x[1]);
        if(unloli>27)
            to=i+1;
    }
    int s=0;
    for(auto[i,j]:cnt)
        s+=(i<unloli)*j;
    calc(to,n-1,s,0);
    return ans;
}

Compilation message (stderr)

prize.cpp: In function 'void calc(int, int, int, int)':
prize.cpp:29:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   29 |     int mid=l+r>>1,pt=mid;
      |             ~^~

• Subtask 1: 20 / 20
• Subtask 2: 80 / 80