Submission #1259469

#	Time	Username	Problem	Language	Result	Execution time	Memory
1259469		sokratisi	Cave (IOI13_cave)	C++20	100 / 100	170 ms	804 KiB

cave

#include "cave.h"
#include <vector>
#include <set>
#include <cstdio>

using namespace std;

set<int> use;
int n;

//vector<int> sa, da;

//int tryCombination(int s[]) {
//    int ans = -1;
//    for (int i = 0; i < n; i++) printf("%d ", s[i]);
//    for (int i = 0; i < n; i++) {
//        if (s[i] != sa[i]) {
//            ans = i;
//            break;
//        }
//    }
//    printf(" -> %d\n", ans);
//    return ans;
//}

pair<int, int> bsearch(int i, int s[]) {
    vector<int> t;
    for (auto u: use) t.push_back(u);

    int cntrl = tryCombination(s);
    if (cntrl == -1) cntrl = n+2;

    int l = 0, r = t.size()-1;
    while(l < r) {
        int m = (l + r) / 2;
        int ts[n];
        for (int i = 0; i < n; i++) ts[i] = s[i];
        for (int i = l; i <= m; i++) {
            ts[t[i]] = 1-ts[t[i]];
        }
        int ans = tryCombination(ts);
        if (ans == -1) ans = n + 2;
        if (cntrl == i && ans > i) r = m;
        else if (cntrl > i && ans == i) r = m;
        else l = m + 1;
    }
    // the switch is t[l]
    int corpos;
    if (cntrl > i) corpos = s[t[l]];
    else corpos = 1 - s[t[l]];
    return {t[l], corpos};
}

void exploreCave(int N) {
    n = N;
    int s[n], d[n];
    for (int i = 0; i < n; i++) s[i] = 0;
    for (int i = 0; i < n; i++) use.insert(i);
    for (int i = 0; i < n; i++) {
        pair<int, int> ans = bsearch(i, s);
        use.erase(ans.first);
        s[ans.first] = ans.second;
        d[ans.first] = i;
    }
    answer(s, d);
    //for (int i = 0; i < n; i++) printf("%d ", s[i]);
    //printf("\n");
    //for (int i = 0; i < n; i++) printf("%d ", d[i]);
    //printf("\n");
}

//int main() {
//    int t;
//    scanf("%d", &t);
//    sa.resize(t);
//    da.resize(t);
//    for (int i = 0; i < t; i++) {
//        scanf("%d%d", &sa[i], &da[i]);
//    }
//    exploreCave(t);
//}

• Subtask 1: 12 / 12
• Subtask 2: 13 / 13
• Subtask 3: 21 / 21
• Subtask 4: 30 / 30
• Subtask 5: 24 / 24