Submission #728122

#	Time	Username	Problem	Language	Result	Execution time	Memory
728122		nguyentunglam	The Big Prize (IOI17_prize)	C++17	100 / 100	71 ms	5308 KiB

prize

#include<bits/stdc++.h>
using namespace std;
#include "prize.h"
//mt19937 rng(172831923);
////mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//int rnd(int l, int r) {
//    return l + rng() % (r - l + 1);
//}

const int N = 2e5 + 10;
vector<int> ans[N];
int worst;
int check(int i, int j) {
    if (ans[i].empty()) ans[i] = ask(i); if (ans[j].empty()) ans[j] = ask(j);
    if (ans[j][0] + ans[j][1] != worst) return 2;
    int tmp = ans[i][1] + ans[j][0] - worst;
    return tmp > 0;
}

int find_best(int n) {

    int T = max(1, n / 785);
    for(int i = 0; i < n; i += T) {
        ans[i] = ask(i);
        worst = max(worst, ans[i][0] + ans[i][1]);
    }

    for(int i = 1; i < n; i++) if (i % T) {
        if (ans[i].empty()) ans[i] = ask(i);
        if (ans[i][0] + ans[i][1] != worst) continue;
        int l = i, r = n - 1;
        for(int j = T; j < n; j += T) if (j > i) {
            if (check(i, j)) {
                r = j;
                break;
            }
            l = j;
        }

        int last = l;
        while (l <= r) {
            int mid = l + r >> 1;
            int tmp = check(i, mid);
            if (!tmp) {
                last = mid;
                l = mid + 1;
            }
            else r = mid - 1;
        }
//        cout << i << " " << last << endl;
        i = last;
    }

    for(int i = 0; i < n; i++) if (!ans[i].empty() && ans[i][0] + ans[i][1] == 0) {
        return i;
    }
    return 0;
}

Compilation message (stderr)

prize.cpp: In function 'int check(int, int)':
prize.cpp:14:5: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   14 |     if (ans[i].empty()) ans[i] = ask(i); if (ans[j].empty()) ans[j] = ask(j);
      |     ^~
prize.cpp:14:42: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   14 |     if (ans[i].empty()) ans[i] = ask(i); if (ans[j].empty()) ans[j] = ask(j);
      |                                          ^~
prize.cpp: In function 'int find_best(int)':
prize.cpp:42:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   42 |             int mid = l + r >> 1;
      |                       ~~^~~

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