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Submission #390262

# Submission time Handle Problem Language Result Execution time Memory
390262 2021-04-15T17:22:04 Z parsabahrami Islands (IOI08_islands) C++17
80 / 100
 1704 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, bads[N / 2], rt[N], P[N], out[N], w[N], R, ptrb, ptrv, b; 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) {
    if (!~b || H[b] < H[v]) b = 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;
        b = -1, preDFS(i, i); 
        A[i] = H[b]; int u = b;
        H[b] = 0, b = -1, preDFS(u, i);
        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:79:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   79 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
islands.cpp:81:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   81 |         scanf("%d%d", &out[i], &w[i]);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 23756 KB Output is correct
2 Correct 15 ms 23884 KB Output is correct
3 Correct 16 ms 23828 KB Output is correct
4 Correct 15 ms 23756 KB Output is correct
5 Correct 15 ms 23756 KB Output is correct
6 Correct 15 ms 23756 KB Output is correct
7 Correct 16 ms 23756 KB Output is correct
8 Correct 15 ms 23756 KB Output is correct
9 Correct 15 ms 23756 KB Output is correct
10 Correct 15 ms 23748 KB Output is correct
11 Correct 15 ms 23844 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 17 ms 23944 KB Output is correct
2 Correct 17 ms 23880 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 23884 KB Output is correct
2 Correct 18 ms 24260 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 26 ms 24852 KB Output is correct
2 Correct 40 ms 27160 KB Output is correct
3 Correct 28 ms 25160 KB Output is correct
4 Correct 21 ms 24380 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 49 ms 28524 KB Output is correct
2 Correct 61 ms 31540 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 120 ms 38084 KB Output is correct
2 Correct 132 ms 43460 KB Output is correct
3 Correct 155 ms 51136 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 204 ms 50884 KB Output is correct
2 Correct 262 ms 70908 KB Output is correct
3 Correct 312 ms 81236 KB Output is correct
4 Correct 353 ms 94148 KB Output is correct

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 389 ms 93476 KB Output is correct
2 Correct 1200 ms 122976 KB Output is correct
3 Correct 383 ms 75712 KB Output is correct
4 Correct 507 ms 110404 KB Output is correct
5 Correct 490 ms 110044 KB Output is correct
6 Correct 1704 ms 79152 KB Output is correct
7 Runtime error 496 ms 131076 KB Execution killed with signal 9

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 393 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -