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Submission #390261

# Submission time Handle Problem Language Result Execution time Memory
390261 2021-04-15T17:17:56 Z parsabahrami Islands (IOI08_islands) C++17
80 / 100
 1779 ms 131076 KB 
/* There's someone in my head but it's not me */ 
#include <bits/stdc++.h>

using namespace std;

typedef long long int ll;
typedef pair<int, int> pii;
 
#define SZ(x)                       (int) x.size()
#define F                           first
#define S                           second

const int N = 1e6 + 1;
int n, vec[N], bads[N / 2], rt[N], P[N], out[N], w[N], R, ptrb, ptrv; ll A[N], ret[N], H[N], S;
vector<int> adj[N]; bitset<N> C;

int Find(int v) {
    return !rt[v] ? v : rt[v] = Find(rt[v]);
}

int Union(int v, int u) {
    u = Find(u), v = Find(v);
    if (u == v) return 1;
    rt[u] = v; 
    return 0;
}

void preDFS(int v, int tr, int p = -1) {
    vec[ptrv++] = v, adj[v].push_back(v);
    for (int &id : adj[v]) {
        int u = out[id] ^ id ^ v;
        if ((!C[u] || u == tr) && u != p) 
            H[u] = H[v] + w[id], preDFS(u, tr, v);
    }
    adj[v].pop_back();
}

void cycDFS(int v, int tr, int p = -1) {
    adj[v].push_back(v);
    for (int &id : adj[v]) {
        if (id != tr) {
            int u = out[id] ^ id ^ v;
            if (u != p) P[u] = id, cycDFS(u, tr, v);
        }
    }
    adj[v].pop_back();
}

ll CYC(int &v, int p = -1) {
    ll ans = -1e18; adj[v].push_back(v);
    for (int &id : adj[v]) {
        int u = out[id] ^ id ^ v;
        if (C[u] && u != p && u != R) {
            H[u] = H[v] + w[id], ans = CYC(u, v);
            break;
        }
    }
    adj[v].pop_back();
    ret[Find(v)] =  max(ret[Find(v)], ans + A[v] - H[v]);
    return max(ans, A[v] + H[v]);
}

ll CYC2(int &v, int p = -1) {
    ll ans = -1e18; adj[v].push_back(v);
    for (int &id : adj[v]) {
        int u = out[id] ^ id ^ v;
        if (C[u] && u != p && u != R) {
            ans = CYC2(u, v);
            break;
        }
    }
    adj[v].pop_back();
    ret[Find(v)] = max(ret[Find(v)], ans + A[v] + H[v]);
    return max(ans, S - H[v] + A[v]);
}

int main() {
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
        scanf("%d%d", &out[i], &w[i]);
        adj[out[i]].push_back(i);
        if (Union(i, out[i])) 
            bads[ptrb++] = i;
    } 
    for (int i = 0; i < ptrb; i++) {
        int &id = bads[i];
        cycDFS(out[id], id); 
        int v = id; C[out[id]] = 1;
        while (P[v]) 
            C[v] = 1, v = out[P[v]] ^ P[v] ^ v;
    } 
    for (int i = 1; i <= n; i++) {
        if (!C[i]) continue;
        ptrv = 0, preDFS(i, i); 
        int b = -1;
        for (int j = 0; j < ptrv; j++) {
            int &v = vec[j];
            if (!~b || H[b] < H[v]) b = v;
        }
        A[i] = H[b]; ptrv = 0;
        H[b] = 0, preDFS(b, i);
        b = -1;
        for (int j = 0; j < ptrv; j++) {
            int &v = vec[j];
            if (!~b || H[b] < H[v]) b = v;
        }
        ret[Find(i)] = max(ret[Find(i)], H[b]);
    }
    ll res = 0; 
    for (int i = 0; i < ptrb; i++) {
        R = bads[i];
        H[R] = 0; S = w[R];
        int v = R; 
        while (P[v]) 
            S += w[P[v]], v = P[v] ^ v ^ out[P[v]];
        CYC(R), CYC2(R);
        res += ret[Find(R)];
    } 
    printf("%lld\n", res);
    return 0;
}

Compilation message

islands.cpp: In function 'int main()':
islands.cpp:78:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   78 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
islands.cpp:80:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   80 |         scanf("%d%d", &out[i], &w[i]);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 23756 KB Output is correct
2 Correct 17 ms 23888 KB Output is correct
3 Correct 18 ms 23884 KB Output is correct
4 Correct 16 ms 23756 KB Output is correct
5 Correct 15 ms 23756 KB Output is correct
6 Correct 15 ms 23780 KB Output is correct
7 Correct 15 ms 23756 KB Output is correct
8 Correct 15 ms 23756 KB Output is correct
9 Correct 15 ms 23812 KB Output is correct
10 Correct 17 ms 23852 KB Output is correct
11 Correct 17 ms 23784 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 23848 KB Output is correct
2 Correct 15 ms 23936 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 23932 KB Output is correct
2 Correct 17 ms 24268 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 25 ms 24964 KB Output is correct
2 Correct 37 ms 27200 KB Output is correct
3 Correct 28 ms 25340 KB Output is correct
4 Correct 21 ms 24512 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 49 ms 28628 KB Output is correct
2 Correct 64 ms 31604 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 120 ms 38248 KB Output is correct
2 Correct 136 ms 43752 KB Output is correct
3 Correct 174 ms 51288 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 200 ms 50476 KB Output is correct
2 Correct 260 ms 70980 KB Output is correct
3 Correct 320 ms 81396 KB Output is correct
4 Correct 353 ms 94276 KB Output is correct

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 394 ms 96936 KB Output is correct
2 Correct 1252 ms 126656 KB Output is correct
3 Correct 380 ms 75844 KB Output is correct
4 Correct 550 ms 110480 KB Output is correct
5 Correct 589 ms 110204 KB Output is correct
6 Correct 1779 ms 81592 KB Output is correct
7 Runtime error 506 ms 131076 KB Execution killed with signal 9

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 387 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -