Submission #668887

#	Time	Username	Problem	Language	Result	Execution time	Memory
668887		a_aguilo	The Big Prize (IOI17_prize)	C++14	90 / 100	54 ms	2000 KiB

prize

#include "prize.h"
#include<bits/stdc++.h>

using namespace std;

int N;
vector<int> LeftVal, RightVal;

int binarySearch(int left, int right){
    int ans = -1;
    if(left+1 >= right) return -1;
    int mid = left + (right - left)/2;
    vector<int> trial = ask(mid);
    LeftVal[mid] = trial[0];
    RightVal[mid] = trial[1];
    if((trial[0] +trial[1]) == 0) return mid;
    int myRight = mid;
    int myLeft = mid;
    while((LeftVal[myLeft] + RightVal[myLeft]) < (LeftVal[left] + RightVal[left])){
        myLeft--;
        trial = ask(myLeft);
        LeftVal[myLeft] = trial[0];
        RightVal[myLeft] = trial[1];
        if((trial[0]+trial[1]) == 0) return myLeft;
    }
    while(((LeftVal[myRight] + RightVal[myRight]) < (LeftVal[left] + RightVal[left])) and (myRight < right)){
        myRight++;
        trial = ask(myRight);
        LeftVal[myRight] = trial[0];
        RightVal[myRight] = trial[1];
        if((trial[0]+trial[1]) == 0) return myRight;
    }
    if((LeftVal[myLeft] - LeftVal[left])  > 0) ans = max(ans, binarySearch(left, myLeft));
    if(myRight < right){
        if(right == N){
            if(RightVal[myRight] > 0) ans = max(ans, binarySearch(myRight, right));
        }
        else{
            if((RightVal[myRight]  - RightVal[right])> 0) ans = max(ans, binarySearch(myRight, right));
        }
    }    
    return ans;
}

int find_best(int n) {
    N = n;
    LeftVal = vector<int>(n, -1);
    RightVal = vector<int>(n, -1);
    vector<int> trial = ask(0);
    int lollipop = 0;
    LeftVal[0] = trial[0];
    RightVal[0] = trial[1];
    if((LeftVal[0] + RightVal[0]) == 0) return 0;
    for(int i = 1; i < min(n, 500); ++i){
        trial = ask(i);
        LeftVal[i] = trial[0];
        RightVal[i] = trial[1];
        if((LeftVal[i]+RightVal[i]) >= (LeftVal[lollipop] + RightVal[lollipop])) lollipop = i;
        if((LeftVal[i] + RightVal[i]) == 0) return i;
    }
    return binarySearch(lollipop, n);
}

• Subtask 1: 20 / 20
• Subtask 2: 70 / 80