Submission #1037612

#	Time	Username	Problem	Language	Result	Execution time	Memory
1037612		Forested	The Big Prize (IOI17_prize)	C++17	90 / 100	61 ms	424 KiB

prize

#include <bits/stdc++.h>
using namespace std;
using i32 = int;
using i64 = long long;
template <typename T>
using V = vector<T>;
template <typename T>
using VV = V<V<T>>;
template <typename T>
using VVV = V<VV<T>>;
template <typename T>
bool chmin(T &x, const T &y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}
template <typename T>
bool chmax(T &x, const T &y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}
#define OVERRIDE4(a, b, c, d, ...) d
#define REP2(i, n) for (i32 i = 0; i < (i32)(n); ++i)
#define REP3(i, l, r) for (i32 i = (i32)(l); i < (i32)(r); ++i)
#define REP(...) OVERRIDE4(__VA_ARGS__, REP3, REP2)(__VA_ARGS__)
#define PER2(i, n) for (i32 i = (i32)(n)-1; i >= 0; --i)
#define PER3(i, l, r) for (i32 i = (i32)(r)-1; i >= (i32)(l); --i)
#define PER(...) OVERRIDE4(__VA_ARGS__, PER3, PER2)(__VA_ARGS__)
#define LEN(x) (i32) size(x)
#define ALL(x) begin(x), end(x)

void dbg(i32 x) { cerr << x; }
void dbg(i64 x) { cerr << x; }
template <typename T, typename U>
void dbg(pair<T, U> p) {
    cerr << "(";
    dbg(p.first);
    cerr << ", ";
    dbg(p.second);
    cerr << ")";
}
template <typename T>
void dbg(V<T> arr) {
    cerr << "[";
    REP(i, LEN(arr)) {
        if (i) {
            cerr << ", ";
        }
        dbg(arr[i]);
    }
    cerr << "]";
}
void debug() { cerr << '\n'; }
template <typename Head, typename... Tail>
void debug(Head head, Tail... tail) {
    dbg(head);
    cerr << ", ";
    debug(tail...);
}
#ifdef DEBUGF
#define DBG(...)                       \
    do {                               \
        cerr << #__VA_ARGS__ << " : "; \
        debug(__VA_ARGS__);            \
    } while (false)
#else
#define DBG(...) (void)0
#endif

#include "prize.h"

pair<i32, i32> ask2(i32 x) {
    static i32 q;
    ++q;
    if (q == 10000) {
        assert(false);
    }
    V<i32> ret = ask(x);
    return pair<i32, i32>(ret[0], ret[1]);
}

i32 subtask_1(i32 n) {
    i32 ok = -1, ng = n - 1;
    while (ng - ok > 1) {
        i32 mid = (ok + ng) / 2;
        auto [l, r] = ask2(mid);
        if (r) {
            ok = mid;
        } else {
            ng = mid;
        }
    }
    return ng;
}

i32 find_best(i32 n) {
    mt19937 mt(random_device{}());
    i32 cands = 0;
    {
        uniform_int_distribution<> dist(0, n - 1);
        REP(i, 50) {
            auto [l, r] = ask2(dist(mt));
            chmax(cands, l + r);
        }
    }
    auto rec = [&](auto rec, i32 l, i32 r, i32 lc, i32 rc) -> i32 {
        i32 tc = cands - lc - rc;
        if (tc == 0) {
            return -1;
        }
        DBG(l, r, lc, rc);
        i32 mid = (l + r) / 2;
        auto [lm, rm] = ask2(mid);
        DBG(mid, lm, rm);
        if (lm + rm == 0) {
            return mid;
        }
        if (lm + rm == cands) {
            i32 tmp = rec(rec, l, mid, lc, rm);
            if (tmp != -1) {
                return tmp;
            }
            return rec(rec, mid, r, lm, rc);
        }
        // to left
        if (lm != 0) {
            i32 x = mid - 1;
            while (x >= l) {
                auto [lx, rx] = ask2(x);
                if (lx + rx == 0) {
                    return x;
                }
                if (lx + rx == cands) {
                    i32 tmp = rec(rec, l, x, lc, rx);
                    if (tmp != -1) {
                        return tmp;
                    }
                    break;
                }
                if (lm == 0) {
                    break;
                }
                --x;
            }
        }
        // to right
        {
            i32 x = mid + 1;
            while (x < r) {
                auto [lx, rx] = ask2(x);
                if (lx + rx == 0) {
                    return x;
                }
                if (lx + rx == cands) {
                    i32 tmp = rec(rec, x + 1, r, lx, rc);
                    if (tmp != -1) {
                        return tmp;
                    }
                    break;
                }
                ++x;
            }
        }
        return -1;
    };
    i32 ans = rec(rec, 0, n, 0, 0);
    return ans;
}

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