Submission #1118921

#	Time	Username	Problem	Language	Result	Execution time	Memory
1118921		gdragon	Growing Vegetable is Fun 3 (JOI19_ho_t3)	C++17	75 / 100	50 ms	772 KiB

joi2019_ho_t3

#include <bits/stdc++.h>
using namespace std;
#define TASK "long"
#define fi first
#define se second
#define ll long long
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define GETBIT(mask, i) ((mask) >> (i) & 1)
#define MASK(i) ((1LL) << (i))
#define SZ(x) ((int)(x).size())
#define mp make_pair
#define CNTBIT(mask) __builtin_popcount(mask)
template<class X, class Y> bool maximize(X &x, Y y){ if (x < y) {x = y; return true;} return false;};
template<class X, class Y> bool minimize(X &x, Y y){ if (x > y) {x = y; return true;} return false;};
typedef pair<int, int> ii;
const int N = 400 + 2;
const int inf = 1e9 + 7;
const long long INF = (long long)1e18 + 7;
const int mod = 1e9 + 7;
struct Fenwick {
    int n;
    vector<int> v;
    Fenwick(int _n = 0) {
        n = _n;
        v.assign(n + 2, 0);
    }
    void update(int x, int c) {
        for(; x <= n; x += x & -x) v[x] += c;
    }
    int get(int x) {
        int ans = 0;
        for(; x > 0; x -= x & -x) ans += v[x];
        return ans;
    }
} fw;
int n;
int a[N];
string s;
void read() {
    cin >> n >> s;
    for(int i = 0; i < n; i++) {
        if (s[i] == 'R') a[i + 1] = 0;
        else if (s[i] == 'G') a[i + 1] = 1;
        else a[i + 1] = 2;
    }
}
bool check3() {
    for(int i = 1; i <= n; i++) if (a[i] == 2) return false;
    return true;
}
void sub3() {
    vector<int> cnt[2];
    for(int i = 1; i <= n; i++) cnt[a[i]].push_back(i);
    if (abs(SZ(cnt[0]) - SZ(cnt[1])) > 1) {
        cout << -1;
        return;
    }
    if (n & 1) {
        if (SZ(cnt[0]) < SZ(cnt[1])) swap(cnt[0], cnt[1]);
        reverse(ALL(cnt[0]));
        reverse(ALL(cnt[1]));
        int ans = 0;
        for(int i = 1; i <= n; i++) {
            int c = 1;
            if (i & 1) c = 0;
            int p = cnt[c].back(); cnt[c].pop_back();
            for(int j = 0; j < 2; j++) {
                for(auto &pos: cnt[j]) if (pos < p) ++pos;
            }
            ans += p - i;
            // cerr << p << ' ' << i << ' ' << ans << endl;
        }
        cout << ans;
    }
    else {
        vector<int> tmp[2];
        tmp[0] = cnt[0];
        tmp[1] = cnt[1];
        int ans = inf;
        for(int iter = 0; iter < 2; iter++) {
            cnt[0] = tmp[0];
            cnt[1] = tmp[1];
            reverse(ALL(cnt[0]));
            reverse(ALL(cnt[1]));
            int res = 0;
            for(int i = 1; i <= n; i++) {
                int c = 1;
                if (i & 1) c = 0;
                int p = cnt[c].back(); cnt[c].pop_back();
                for(int j = 0; j < 2; j++) {
                    for(auto &pos: cnt[j]) if (pos < p) ++pos;
                }
                res += p - i;
            }
            ans = min(ans, res);
            swap(tmp[0], tmp[1]);
        }
        cout << ans;
    }
}
void sub1() {
    vector<int> cnt[3], tmp[3];
    for(int i = 1; i <= n; i++) cnt[a[i]].push_back(i);
    for(int i = 0; i < 3; i++) {
        reverse(ALL(cnt[i]));
        tmp[i] = cnt[i];
    }
    sort(a + 1, a + n + 1);
    int ans = inf;
    do {
        for(int i = 0; i < 3; i++) cnt[i] = tmp[i];
        int res = 0;
        for(int i = 1; i <= n; i++) {
            if (i > 1 && a[i] == a[i - 1]) {
                res = inf;
                break;
            } 
            int p = cnt[a[i]].back(); cnt[a[i]].pop_back();
            for(int j = 0; j < 3; j++) {
                for(auto &pos: cnt[j]) if (pos < p) ++pos;
            }
            res += p - i;
            // cerr << p << ' ' << i << ' ' << ans << endl;
        }
        ans = min(ans, res);
    }
    while(next_permutation(a + 1, a + n + 1));
    cout << (ans == inf ? -1 : ans);
}
void sub2() {
    fw = Fenwick(n);
    vector<int> pos[3];
    for(int i = 1; i <= n; i++) pos[a[i]].push_back(i);
    vector<vector<vector<int>>> dp[3];
    for(int i = 0; i < 3; i++) {
        dp[i].assign(SZ(pos[0]) + 1, vector<vector<int>>(SZ(pos[1]) + 1, vector<int>(SZ(pos[2]) + 1, inf)));
    }
    vector<tuple<int, int, int>> upd[n + 1];
    for(int i = 0; i <= SZ(pos[0]); i++) {
        for(int j = 0; j <= SZ(pos[1]); j++) {
            for(int z = 0; z <= SZ(pos[2]); z++) {
                // cerr << i + j + z << ' ' << i << ' ' << j << ' ' << z << endl;
                upd[i + j + z].push_back({i, j, z});
            }
        }
    }
    for(int i = 0; i < 2; i++) dp[i][0][0][0] = 0;
    auto countLess = [&](tuple<int, int, int> sz, int p) -> int {
        // return 0;
        int cnt = 0;
        int s[] = {get<0>(sz), get<1>(sz), get<2>(sz)};
        for(int i = 0; i < 3; i++) {
            int t = lower_bound(pos[i].begin(), pos[i].begin() + s[i], p) - pos[i].begin();
            cnt += s[i] - t;
        }
         // if (p == 1) cout << cnt << endl;
        // if (p == 1) cout << cnt << endl;
        return cnt;
    };
    for(int i = 0; i < n; i++) {
        for(auto j: upd[i]) {
            int c0 = get<0>(j);
            int c1 = get<1>(j);
            int c2 = get<2>(j);
            for(int last = 0; last < 3; last++) {
                if (dp[last][c0][c1][c2] < inf) {
                    // cerr << c0 << ' ' << c1 << ' ' << c2 << ' ' << last << ' ' << dp[last][c0][c1][c2] << endl;
                    tuple<int, int, int> sz = {c0, c1, c2};
                    int tmp = dp[last][c0][c1][c2];
                    if (last != 0 && c0 < SZ(pos[0])) {
                        int p = pos[0][c0];
                        int less = countLess(sz, p);
                        int cost = p + less - (i + 1);
                        minimize(dp[0][c0 + 1][c1][c2], tmp + cost);
                    }
                    if (last != 1 && c1 < SZ(pos[1])) {
                        int p = pos[1][c1];
                        int less = countLess(sz, p);
                        int cost = p + less - (i + 1);
                        minimize(dp[1][c0][c1 + 1][c2], tmp + cost);
                    }
                    if (last != 2 && c2 < SZ(pos[2])) {
                        int p = pos[2][c2];
                        int less = countLess(sz, p);
                        int cost = p + less - (i + 1);
                        minimize(dp[2][c0][c1][c2 + 1], tmp + cost);
                    }
                }
            }
        }
    }
    int ans = inf;
    for(int i = 0; i < 3; i++) ans = min(ans, dp[i][SZ(pos[0])][SZ(pos[1])][SZ(pos[2])]);
    cout << (ans == inf ? -1 : ans);
}
void solve() {
    if (check3()) sub3();
    else if (n <= 15) sub1();
    else if (n <= 60) sub2();
}
signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if (fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
    int test = 1;
    // cin >> test;
    while(test--) {
        read();
        solve();
    }
    return 0;
}

// rmq - rmq2d
// hash
// fw - fw2d
// segtree

Compilation message (stderr)

joi2019_ho_t3.cpp: In function 'int main()':
joi2019_ho_t3.cpp:205:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  205 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
joi2019_ho_t3.cpp:206:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  206 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 55 / 55
• Subtask 3: 15 / 15
• Subtask 4: 0 / 25