Submission #906048

#	Time	Username	Problem	Language	Result	Execution time	Memory
906048		nightfal	The Big Prize (IOI17_prize)	C++14	100 / 100	29 ms	692 KiB

prize

//#include "prize.h"
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

static const int max_q = 10000;
static int n;
static int query_count = 0;
static vector<int> g;
static vector<vector<int> > rank_count;

int find_best(int n);
std::vector<int> ask(int i);

int subtask0(int n) {
    std::vector<int> ans;
    for(int i=0; i<n; i++) {
        ans = ask(i); 
        if(ans[0]+ans[1]==0) return i;
    }
}

int subtask1(int n){
    int start=0, end=n-1;
    while (start<end) {
        int mid = (start+end)/2;
        vector<int> ans = ask(mid);
        if (!ans[0] && !ans[1]) return mid;
        else if (!ans[0]) start=mid+1;
        else end = mid-1;
    }
    return start;
}

// int bSearch(int start, int end, std::vector<int>& sAns, std::vector<int>& eAns, int maxVal) {
//     printf("start=%d, end=%d, ",start,end);
//     printf("sAns[%d]={%d,%d}, ",start,sAns[0],sAns[1]);
//     printf("eAns[%d]={%d,%d}\n ",start,eAns[0],eAns[1]);
//     int result = -1;
//     if (eAns[0]==sAns[0]) return -1;
//     int mid = (start+end+1)/2;
//     printf("mid=%d ",mid);
//     vector<int> mAns = ask(mid);
//     if (mAns[0]+mAns[1]==0) return mid;
//     int midL=mid, midR=mid;

//     if(mAns[0]+mAns[1]<maxVal) {
//         midL = start;
//         for(int i=mid-1; i>start; i--) {
//             mAns = ask(i);
//             if(mAns[0]+mAns[1]==0) return i;
//             if(mAns[0]+mAns[1]==maxVal) {midL=i; break;}
//         }
//         midR = end;
//         for(int i=mid+1; i<end; i++) {
//             mAns = ask(i);
//             if(mAns[0]+mAns[1]==0) return i;
//             if(mAns[0]+mAns[1]==maxVal) {midR=i; break;}
//         }
//     }
//     printf("midL=%d, midR=%d\n",midL,midR);
//     if (start<midL) result = bSearch(start,midL,sAns,mAns,maxVal);
//     if (result != -1) return result;
//     if(midR<end) return bSearch(midR,end,mAns,eAns,maxVal);
//     return -1;
// }

int bSearch(int start, int end, std::vector<int>& sAns, std::vector<int>& eAns) {
    // printf("start=%d, end=%d, ",start,end);
    // printf("sAns={%d,%d}, ",sAns[0],sAns[1]);
    // printf("eAns={%d,%d}\n ",eAns[0],eAns[1]);
    int result = -1;
    if(start+1 == end) return -1;
    if (eAns[0]==sAns[0]) return -1;
    int mid = (start+end+1)/2;
    // printf("mid=%d, ",mid);
    vector<int> mAns = ask(mid);
    if (mAns[0]+mAns[1]==0) return mid;
    int midL=mid, midR=mid;
    vector<int> midLAns = mAns, midRAns = mAns;

    while(sAns[0]+sAns[1]!=midLAns[0]+midLAns[1] && start + 1 < midL) {
        if (sAns[0]+sAns[1] < midLAns[0]+midLAns[1]) {
            sAns = ask(++start);
            if (sAns[0]+sAns[1]==0) return start;
        }
        else {
            midLAns = ask(--midL);
            if (midLAns[0]+midLAns[1]==0) return midL;
        }
    }
    if (start + 1 < midL) result = bSearch(start,midL,sAns,midLAns);
    if (result != -1) return result;
    
    while(midRAns[0]+midRAns[1]!=eAns[0]+eAns[1] && midR + 1 < end) {
        if (midRAns[0]+midRAns[1] < eAns[0]+midRAns[1]) {
            midRAns = ask(++midR);
            if (midRAns[0]+midRAns[1]==0) return midR;
        }
        else {
            eAns = ask(--end);
            if (eAns[0]+eAns[1]==0) return end;
        }
    }
    // printf("midL=%d, midR=%d\n",midL,midR);
    if(midR + 1 < end) return bSearch(midR,end,midRAns,eAns);
    return -1;
}
int find_best(int n) {
    // if (n<=5000) {return subtask0(n);}

    // int m = min(500,n), maxVal=0, maxIdx=-1;
	// for(int i=0; i<m; i++) {
    //     ans[i] = ask(i);
    //     int sum = ans[i][0]+ans[i][1];
    //     // if(sum==0) return i;
    //     if (maxVal<sum) {maxVal=sum; maxIdx=i;}
    // }
    // printf("maxVal:%d, maxIdx:%d\n",maxVal,maxIdx);
    int start=0, end=n-1;
    vector<int> sAns=ask(start), eAns=ask(end);
    if (sAns[0]+sAns[1]==0) return start;
    if (eAns[0]+eAns[1]==0) return end;

    while(sAns[0]+sAns[1]!=eAns[0]+eAns[1]) {
        if (sAns[0]+sAns[1] < eAns[0]+eAns[1]) {
            sAns = ask(++start);
            if (sAns[0]+sAns[1]==0) return start;
        }
        else {
            eAns = ask(--end);
            if (eAns[0]+eAns[1]==0) return end;
        }
    }
    // assert sAns[0]+sAns[1]==eAns[0]+eAns[1] && start < end;
	return bSearch(start,end,sAns,eAns);
}

Compilation message (stderr)

prize.cpp: In function 'int subtask0(int)':
prize.cpp:18:22: warning: control reaches end of non-void function [-Wreturn-type]
   18 |     std::vector<int> ans;
      |                      ^~~
prize.cpp: At global scope:
prize.cpp:10:12: warning: 'query_count' defined but not used [-Wunused-variable]
   10 | static int query_count = 0;
      |            ^~~~~~~~~~~
prize.cpp:9:12: warning: 'n' defined but not used [-Wunused-variable]
    9 | static int n;
      |            ^

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