Submission #842621

#	Time	Username	Problem	Language	Result	Execution time	Memory
842621		WLZ	Prisoner Challenge (IOI22_prison)	C++17	100 / 100	14 ms	1132 KiB

prison

#include "prison.h"
#include <bits/stdc++.h>
using namespace std;

int n;

tuple<int, int, int> get_range(int x, int idx) {
    int l = 1, r = n, part;
    for (int i = 0; i <= idx; i++) {
        if (x == l) return {-1, -1, -1};
        if (x == r) return {-2, -2, -2};
        l++; r--;
        int len = r - l + 1;
        int sz1 = len / 3 + (len % 3 >= 1), sz2 = len / 3 + (len % 3 >= 2), sz3 = len / 3;
        int m1 = l + sz1 - 1, m2 = l + sz1 + sz2 - 1;
        if (x <= m1) {
            part = 0;
            r = m1;
        } else if (x <= m2) {
            part = 1;
            l = m1 + 1, r = m2;
        } else {
            part = 2;
            l = m2 + 1;
        }
    }
    return {l, r, part};
}

int get(int x, int idx) {
    auto p = get_range(x, idx);
    if (get<0>(p) == -1) return -1;
    if (get<0>(p) == -2) return 3;
    return get<2>(p);
}

vector< vector<int> > devise_strategy(int N) {
    n = N;
    vector< vector<int> > s(21, vector<int>(N + 1));
    s[0][0] = 0;
    for (int x = 1; x <= N; x++) {
        int tmp = get(x, 0);
        if (tmp == -1) s[0][x] = -1;
        else if (tmp == 3) s[0][x] = -2;
        else s[0][x] = tmp + 1;
    }
    for (int i = 0; i < 6; i++) {
        for (int j = 0; j < 3; j++) {
            int idx = i * 3 + j + 1;
            s[idx][0] = 1 - (i % 2);
            for (int x = 1; x <= N; x++) {
                if (get(x, i) < j) {
                    if (i % 2 == 0) s[idx][x] = -2;
                    else s[idx][x] = -1; 
                } else if (get(x, i) > j) {
                    if (i % 2 == 0) s[idx][x] = -1;
                    else s[idx][x] = -2;
                } else {
                    auto p = get_range(x, i);
                    int l = get<0>(p), r = get<1>(p), part = get<2>(p);
                    if (x == l) {
                        if (i % 2 == 0) s[idx][x] = -2;
                        else s[idx][x] = -1;
                    } else if (x == r) {
                        if (i % 2 == 0) s[idx][x] = -1;
                        else s[idx][x] = -2;
                    } else {
                        if (i < 5) {
                            s[idx][x] = (i + 1) * 3 + get(x, i + 1) + 1;
                        } else {
                            l++; r--;
                            if (x <= (l + r) / 2) s[idx][x] = 19;
                            else s[idx][x] = 20;
                        }
                    }   
                }
            }
        }
    }
    s[19][0] = s[20][0] = 1;
    for (int x = 1; x <= N; x++) {
        auto p = get_range(x, 5);
        int l = get<0>(p) + 1, r = get<1>(p) - 1;
        if (x == l - 1) {
            s[19][x] = s[20][x] = -2;
        } else if (x == r + 1) {
            s[19][x] = s[20][x] = -1;
        } else if (x <= (l + r) / 2) {
            s[20][x] = -2;
            if (x == l) s[19][x] = -2;
            else s[19][x] = -1;
        } else {
            s[19][x] = -1;
            if (x == r) s[20][x] = -1;
            else s[20][x] = -2;
        }
    }
    return s;
}

Compilation message (stderr)

prison.cpp: In function 'std::tuple<int, int, int> get_range(int, int)':
prison.cpp:14:77: warning: unused variable 'sz3' [-Wunused-variable]
   14 |         int sz1 = len / 3 + (len % 3 >= 1), sz2 = len / 3 + (len % 3 >= 2), sz3 = len / 3;
      |                                                                             ^~~
prison.cpp: In function 'std::vector<std::vector<int> > devise_strategy(int)':
prison.cpp:60:55: warning: unused variable 'part' [-Wunused-variable]
   60 |                     int l = get<0>(p), r = get<1>(p), part = get<2>(p);
      |                                                       ^~~~

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 90 / 90