Submission #949747

#	Time	Username	Problem	Language	Result	Execution time	Memory
949747		qin	The Big Prize (IOI17_prize)	C++17	100 / 100	33 ms	688 KiB

prize

#include <bits/stdc++.h>
#include "prize.h"
#define fi first
#define se second
#define ssize(x) int(x.size())
#define pn printf("\n")
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(), x.rend()
#define vv vector
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
int inf = 2e09; ll infll = 2e18; int mod = 119<<23|1;
//~ #ifdef LOCAL
//~ vector<int> ask(int i){ return vector<int>(2, 0); }
//~ #endif
int SUM; // bound na checka, czy to jest gosc z lepszej, czy nie
mt19937 rng(34);
int f(int l, int r, int resl, int resr){
		//~ printf("%d %d\n", l, r);
		int midl = (l+r)/2, midr = (l+r)/2;
		int result = 0;
		
		vv<int> tmp = ask(midl), tmp2 = tmp; int sum = tmp[0]+tmp[1];
		while(sum != SUM && l < midl-1){
				if(!sum){ return midl;}
				--midl;
				tmp = ask(midl); sum = tmp[0]+tmp[1];
		}
		if(!sum) return midl;
		if(sum == SUM && resl != tmp[0]) result = max(result, f(l, midl, resl, tmp[0]));
		
		sum = tmp2[0]+tmp2[1];
		while(sum != SUM && midr+1 < r){
				if(!sum) return midr;
				++midr;
				tmp = ask(midr); sum = tmp[0]+tmp[1];
		}
		if(!sum) return midr;
		if(sum == SUM && resr != tmp[0]) result = max(result, f(midr, r, tmp[0], resr));
		
		return result;
}
int find_best(int n){
		//~ if(n <= 5000){
				//~ vv<int> tmp; int result = 0;
				//~ for(int i = 0; i < n; ++i){
						//~ tmp = ask(i);
						//~ if(!(tmp[0]+tmp[1])){ result = i; break; }
				//~ } return result;
		//~ }
		for(int i = 0; i < 50; ++i){
				int x = rng()%n;
				vv<int> tmp = ask(x); int sum = tmp[0]+tmp[1];
				SUM = max(SUM, sum);
				if(!sum) return x;
		}
		int l = 0, r = n-1, resl = 0, resr = 0;
		vv<int> tmp;
		for(int i = 0; i < n; ++i){
				tmp = ask(i); int sum = tmp[0]+tmp[1];
				if(sum == SUM){ l = i, resl = tmp[0]; break; }
				else if(!sum) return i;
		}
		for(int i = n-1; ~i; --i){
				tmp = ask(i); int sum = tmp[0]+tmp[1];
				if(sum == SUM){ r = i, resr = tmp[0]; break; }
				else if(!sum) return i;
		}
		return f(l, r, resl, resr);
}
//~ #ifdef LOCAL
//~ int main(){
		//~ int T = 1;
		//~ for(++T; --T; ) find_best(T);
		//~ return 0;
//~ }
//~ #endif

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