oj.uz

Submission #720983

# Submission time Handle Problem Language Result Execution time Memory
720983 2023-04-10T01:48:41 Z joelgun14 Monochrome Points (JOI20_monochrome) C++17
100 / 100
 112 ms 9368 KB 
#include <bits/stdc++.h>
using namespace std;
int prefb[400005], prefw[400005];
vector<int> b, w;
int n;
long long memo[400005];
long long get_ans(int idx) {
    if(memo[idx] != -1)
        return memo[idx];
    idx += 4 * n;
    idx %= n;
    long long res = 0;
    for(int j = 0; j < n; ++j) {
        int l = b[j], r = w[(idx + j) % n];
        //cout << l << " " << r << endl;
        // cari antara l dan r
        // kalo misal r < l, maka + 2 * n
        if(r < l)
            swap(l, r);
        // pref[2 * n] - pref[r] + pref[l] buat seg 1
        // pref[r] - pref[l] buat seg 2
        int b1 = prefb[2 * n] - prefb[r] + prefb[l - 1], w1 = prefw[2 * n] - prefw[r] + prefw[l - 1];
        int b2 = prefb[r - 1] - prefb[l], w2 = prefw[r - 1] - prefw[l];
        //cout << b1 << " " << b2 << " " << w1 << " " << w2 << endl;
        res += min(b1, w2) + min(b2, w1);
    }
    //cout << idx << " " << res << endl;
    return memo[idx] = res;
}
int main() {
    cin >> n;
    string s;
    cin >> s;
    for(int i = 0; i < 2 * n; ++i) {
        if(s[i] == 'B')
            b.push_back(i + 1);
        else
            w.push_back(i + 1);
    }
    //cout << "TEST" << endl;
    for(int i = 1; i <= 2 * n; ++i) {
        prefb[i] = prefb[i - 1];
        prefw[i] = prefw[i - 1];
        if(binary_search(b.begin(), b.end(), i))
            prefb[i]++;
        else
            prefw[i]++;
    }
    //cout << "PREF BUILD DONE" << endl;
    //cout << b.size() << " " << w.size() << endl;
    // try circular ternary search
    // try shiftnya banyak
    // kalo 2 arah negatif -> binser pisah 2 arah
    // kalo 2 arah positif -> answer
    // pick arbitrary index then check whether it is 2 arah negatif, 2 arah positif, or 1 arah negatif 1 arah positif
    // 2 arah positif -> answer
    // 2 arah negatif -> ternary left and right segments
    // 1 arah negatif 1 arah positif -> pergi ke arah negatif sampe ketemu index pertama yang positif kanannya
    memset(memo, -1, sizeof(memo));
    // pick arbitrary index
    // cari first positive di kanan dan first positive di kiri
    // answer antara cur
    // coba get_ans n / 2, n / 2 - 1 dan n / 2 + 1
    // assume optimal placement cuma ada 1
    // find max antara 0...n - 1
    // find last index such that val[i] >= val[0] jika n - 1 ke 0 increasing
    // jika decreasing cari smallest index yg val[i] >= val[n - 1]
    // nanti dapet rangenya, bs di ternary
    int lb, rb;
    if(get_ans(0) >= get_ans(n - 1)) {
        // find last index where get_ans(i) >= get_ans(0)
        int l = 0, r = n - 1, idx;
        while(l <= r) {
            int mid = (l + r) / 2;
            if(get_ans(mid) >= get_ans(0)) {
                l = mid + 1;
                idx = mid;
            }
            else {
                r = mid - 1;
            }
        }
        lb = 0, rb = idx;
    }
    else {
        // find smallest index where get_ans(i) >= get_ans(n - 1)
        int l = 0, r = n - 1, idx;
        while(l <= r) {
            int mid = (l + r) / 2;
            if(get_ans(mid) >= get_ans(n - 1)) {
                r = mid - 1, idx = mid;
            }
            else {
                l = mid + 1;
            }
        }
        lb = idx, rb = n - 1;
    }
    while(lb < rb) {
        int m1 = lb + (rb - lb) / 3, m2 = lb + 2 * (rb - lb) / 3;
        if(m1 == m2)
            ++m2;
        if(get_ans(m1) >= get_ans(m2))
            rb = m2 - 1;
        else
            lb = m1 + 1;
    }
    //cout << lb << endl;
    cout << get_ans(lb) / 2 << endl;
}

Compilation message

monochrome.cpp: In function 'int main()':
monochrome.cpp:100:27: warning: 'rb' may be used uninitialized in this function [-Wmaybe-uninitialized]
  100 |         int m1 = lb + (rb - lb) / 3, m2 = lb + 2 * (rb - lb) / 3;
      |                       ~~~~^~~~~
monochrome.cpp:100:38: warning: 'lb' may be used uninitialized in this function [-Wmaybe-uninitialized]
  100 |         int m1 = lb + (rb - lb) / 3, m2 = lb + 2 * (rb - lb) / 3;
      |                                      ^~

Subtask #1
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 3412 KB Output is correct
2 Correct 2 ms 3412 KB Output is correct
3 Correct 2 ms 3412 KB Output is correct
4 Correct 2 ms 3412 KB Output is correct
5 Correct 2 ms 3412 KB Output is correct
6 Correct 3 ms 3412 KB Output is correct
7 Correct 2 ms 3412 KB Output is correct
8 Correct 1 ms 3412 KB Output is correct
9 Correct 2 ms 3412 KB Output is correct
10 Correct 2 ms 3412 KB Output is correct
11 Correct 2 ms 3412 KB Output is correct
12 Correct 1 ms 3412 KB Output is correct
13 Correct 2 ms 3412 KB Output is correct

Subtask #2
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 3412 KB Output is correct
2 Correct 2 ms 3412 KB Output is correct
3 Correct 2 ms 3412 KB Output is correct
4 Correct 2 ms 3412 KB Output is correct
5 Correct 2 ms 3412 KB Output is correct
6 Correct 3 ms 3412 KB Output is correct
7 Correct 2 ms 3412 KB Output is correct
8 Correct 1 ms 3412 KB Output is correct
9 Correct 2 ms 3412 KB Output is correct
10 Correct 2 ms 3412 KB Output is correct
11 Correct 2 ms 3412 KB Output is correct
12 Correct 1 ms 3412 KB Output is correct
13 Correct 2 ms 3412 KB Output is correct
14 Correct 2 ms 3412 KB Output is correct
15 Correct 2 ms 3412 KB Output is correct
16 Correct 3 ms 3412 KB Output is correct
17 Correct 2 ms 3412 KB Output is correct
18 Correct 2 ms 3412 KB Output is correct
19 Correct 2 ms 3412 KB Output is correct
20 Correct 2 ms 3412 KB Output is correct
21 Correct 1 ms 3412 KB Output is correct
22 Correct 2 ms 3412 KB Output is correct
23 Correct 2 ms 3412 KB Output is correct
24 Correct 2 ms 3412 KB Output is correct
25 Correct 2 ms 3412 KB Output is correct
26 Correct 2 ms 3412 KB Output is correct
27 Correct 2 ms 3412 KB Output is correct
28 Correct 2 ms 3412 KB Output is correct
29 Correct 3 ms 3412 KB Output is correct
30 Correct 2 ms 3412 KB Output is correct
31 Correct 2 ms 3412 KB Output is correct
32 Correct 2 ms 3412 KB Output is correct
33 Correct 2 ms 3412 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 3412 KB Output is correct
2 Correct 2 ms 3412 KB Output is correct
3 Correct 2 ms 3412 KB Output is correct
4 Correct 2 ms 3412 KB Output is correct
5 Correct 2 ms 3412 KB Output is correct
6 Correct 3 ms 3412 KB Output is correct
7 Correct 2 ms 3412 KB Output is correct
8 Correct 1 ms 3412 KB Output is correct
9 Correct 2 ms 3412 KB Output is correct
10 Correct 2 ms 3412 KB Output is correct
11 Correct 2 ms 3412 KB Output is correct
12 Correct 1 ms 3412 KB Output is correct
13 Correct 2 ms 3412 KB Output is correct
14 Correct 2 ms 3412 KB Output is correct
15 Correct 2 ms 3412 KB Output is correct
16 Correct 3 ms 3412 KB Output is correct
17 Correct 2 ms 3412 KB Output is correct
18 Correct 2 ms 3412 KB Output is correct
19 Correct 2 ms 3412 KB Output is correct
20 Correct 2 ms 3412 KB Output is correct
21 Correct 1 ms 3412 KB Output is correct
22 Correct 2 ms 3412 KB Output is correct
23 Correct 2 ms 3412 KB Output is correct
24 Correct 2 ms 3412 KB Output is correct
25 Correct 2 ms 3412 KB Output is correct
26 Correct 2 ms 3412 KB Output is correct
27 Correct 2 ms 3412 KB Output is correct
28 Correct 2 ms 3412 KB Output is correct
29 Correct 3 ms 3412 KB Output is correct
30 Correct 2 ms 3412 KB Output is correct
31 Correct 2 ms 3412 KB Output is correct
32 Correct 2 ms 3412 KB Output is correct
33 Correct 2 ms 3412 KB Output is correct
34 Correct 3 ms 3412 KB Output is correct
35 Correct 2 ms 3412 KB Output is correct
36 Correct 2 ms 3412 KB Output is correct
37 Correct 2 ms 3412 KB Output is correct
38 Correct 2 ms 3412 KB Output is correct
39 Correct 2 ms 3412 KB Output is correct
40 Correct 3 ms 3412 KB Output is correct
41 Correct 2 ms 3412 KB Output is correct
42 Correct 2 ms 3412 KB Output is correct
43 Correct 2 ms 3412 KB Output is correct
44 Correct 3 ms 3412 KB Output is correct
45 Correct 2 ms 3412 KB Output is correct
46 Correct 2 ms 3412 KB Output is correct
47 Correct 2 ms 3412 KB Output is correct
48 Correct 2 ms 3412 KB Output is correct
49 Correct 4 ms 3412 KB Output is correct
50 Correct 3 ms 3540 KB Output is correct
51 Correct 2 ms 3412 KB Output is correct
52 Correct 2 ms 3412 KB Output is correct

Subtask #4
65.0 / 65.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 3412 KB Output is correct
2 Correct 2 ms 3412 KB Output is correct
3 Correct 2 ms 3412 KB Output is correct
4 Correct 2 ms 3412 KB Output is correct
5 Correct 2 ms 3412 KB Output is correct
6 Correct 3 ms 3412 KB Output is correct
7 Correct 2 ms 3412 KB Output is correct
8 Correct 1 ms 3412 KB Output is correct
9 Correct 2 ms 3412 KB Output is correct
10 Correct 2 ms 3412 KB Output is correct
11 Correct 2 ms 3412 KB Output is correct
12 Correct 1 ms 3412 KB Output is correct
13 Correct 2 ms 3412 KB Output is correct
14 Correct 2 ms 3412 KB Output is correct
15 Correct 2 ms 3412 KB Output is correct
16 Correct 3 ms 3412 KB Output is correct
17 Correct 2 ms 3412 KB Output is correct
18 Correct 2 ms 3412 KB Output is correct
19 Correct 2 ms 3412 KB Output is correct
20 Correct 2 ms 3412 KB Output is correct
21 Correct 1 ms 3412 KB Output is correct
22 Correct 2 ms 3412 KB Output is correct
23 Correct 2 ms 3412 KB Output is correct
24 Correct 2 ms 3412 KB Output is correct
25 Correct 2 ms 3412 KB Output is correct
26 Correct 2 ms 3412 KB Output is correct
27 Correct 2 ms 3412 KB Output is correct
28 Correct 2 ms 3412 KB Output is correct
29 Correct 3 ms 3412 KB Output is correct
30 Correct 2 ms 3412 KB Output is correct
31 Correct 2 ms 3412 KB Output is correct
32 Correct 2 ms 3412 KB Output is correct
33 Correct 2 ms 3412 KB Output is correct
34 Correct 3 ms 3412 KB Output is correct
35 Correct 2 ms 3412 KB Output is correct
36 Correct 2 ms 3412 KB Output is correct
37 Correct 2 ms 3412 KB Output is correct
38 Correct 2 ms 3412 KB Output is correct
39 Correct 2 ms 3412 KB Output is correct
40 Correct 3 ms 3412 KB Output is correct
41 Correct 2 ms 3412 KB Output is correct
42 Correct 2 ms 3412 KB Output is correct
43 Correct 2 ms 3412 KB Output is correct
44 Correct 3 ms 3412 KB Output is correct
45 Correct 2 ms 3412 KB Output is correct
46 Correct 2 ms 3412 KB Output is correct
47 Correct 2 ms 3412 KB Output is correct
48 Correct 2 ms 3412 KB Output is correct
49 Correct 4 ms 3412 KB Output is correct
50 Correct 3 ms 3540 KB Output is correct
51 Correct 2 ms 3412 KB Output is correct
52 Correct 2 ms 3412 KB Output is correct
53 Correct 101 ms 8924 KB Output is correct
54 Correct 106 ms 9368 KB Output is correct
55 Correct 103 ms 9028 KB Output is correct
56 Correct 102 ms 9044 KB Output is correct
57 Correct 89 ms 8944 KB Output is correct
58 Correct 93 ms 8928 KB Output is correct
59 Correct 91 ms 8804 KB Output is correct
60 Correct 90 ms 9088 KB Output is correct
61 Correct 109 ms 9120 KB Output is correct
62 Correct 95 ms 9132 KB Output is correct
63 Correct 92 ms 9052 KB Output is correct
64 Correct 83 ms 8840 KB Output is correct
65 Correct 91 ms 8852 KB Output is correct
66 Correct 86 ms 8876 KB Output is correct
67 Correct 81 ms 8788 KB Output is correct
68 Correct 76 ms 8524 KB Output is correct
69 Correct 92 ms 9132 KB Output is correct
70 Correct 85 ms 8552 KB Output is correct
71 Correct 45 ms 9016 KB Output is correct
72 Correct 49 ms 8932 KB Output is correct
73 Correct 112 ms 9300 KB Output is correct