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Submission #172620

# Submission time Handle Problem Language Result Execution time Memory
172620 2020-01-02T08:20:26 Z rama_pang Bridges (APIO19_bridges) C++14
100 / 100
 2496 ms 7440 KB 
#include <bits/stdc++.h>
using namespace std;
const int BLOCK = 850;

struct RollbackDSU {
    vector<int> root; // parent
    vector<int> sz; // size
    vector<pair<int, int>> operations; // (modified_id, size[id]). If size[id] == -1, then the parent changes

    void init(int n) {
        sz.assign(n, 1);
        root.assign(n, 0);
        iota(begin(root), end(root), 0);
    }

    int find(int n) {
        while (root[n] != n) {
            n = root[n];
        }
        return n;
    }

    bool join(int a, int b, bool revert = false) {
        a = find(a);
        b = find(b);
        if (a == b) {
            return false;
        }
        if (sz[a] < sz[b]) {
            swap(a, b);
        }
        if (revert) {
            operations.emplace_back(b, -1); // b's parent changes
            operations.emplace_back(a, sz[a]); // a's previous size
        }
        sz[a] += sz[b];
        root[b] = a;
        return true;
    }

    void rollback() {
        reverse(begin(operations), end(operations));
        for (auto& op : operations) {
            if (op.second == -1) {
                root[op.first] = op.first;
            } else {
                sz[op.first] = op.second;
            }
        }
        operations.clear();
    }
    
    int getSize(int n) {
        return sz[find(n)];
    }

};

struct Edge {
    int u, v, weight;
    Edge(int u, int v, int w) : u(u), v(v), weight(w) {}
    bool operator<(const Edge& o) const {
        return weight > o.weight;
    }
};

struct Query {
    int start, weight, time;
    Query(int s, int w, int t) : start(s), weight(w), time(t) {}
    bool operator<(const Query& o) const {
        return weight > o.weight;
    }
};

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);

    int n, m;
    cin >> n >> m;

    vector<Edge> edge;
    vector<pair<int, int>> update(m, make_pair(-1, -1)); // (weight, update_time)

    for (int i = 0; i < m; i++) {
        int u, v, w;
        cin >> u >> v >> w;
        u--, v--;
        edge.emplace_back(u, v, w);
    }

    int q;
    cin >> q;

    RollbackDSU DSU;
    vector<pair<int, int>> ans; // (time, answer)

    for (int qi = 0; qi < q; qi += BLOCK) {
        vector<Query> query; // query: (time, start, weight)
        vector<tuple<int, int, int, int>> changed; // (id, weight, time1, time2) -> the id-th edge has weight for time peirod [time1, time2]
        vector<Edge> unchanged; // ids of unchanged edges

        DSU.init(n);

        for (int i = qi; i < qi + BLOCK && i < q; i++) {
            int t, a, b;
            cin >> t >> a >> b;
            a--;

            if (t == 1) {
                if (update[a] == make_pair(-1, -1)) {
                    update[a].first = edge[a].weight;
                }
                changed.emplace_back(a, update[a].first, update[a].second, i - 1); // the current weight lasts between (t1, t2)
                update[a] = {b, i};
            } else if (t == 2) {
                query.emplace_back(a, b, i);
            }
        }

        for (int i = 0; i < m; i++) {
            if (update[i] != make_pair(-1, -1)) {
                changed.emplace_back(i, update[i].first, update[i].second, qi + BLOCK);

                // Update original edge's weight with latest update
                edge[i].weight = update[i].first;
                update[i] = make_pair(-1, -1);
            } else {
                unchanged.emplace_back(edge[i]);
            }
        }

        sort(begin(unchanged), end(unchanged));
        sort(begin(query), end(query));

        for (int i = 0, j = 0; i < query.size(); i++) { // O(BLOCK) iterations
            while (j < unchanged.size() && unchanged[j].weight >= query[i].weight) {
                DSU.join(unchanged[j].u, unchanged[j].v);
                j++;
            }

            for (auto& c : changed) { // O(BLOCK log n)
                int id, w, t1, t2;
                tie(id, w, t1, t2) = c;
                if (t1 <= query[i].time && query[i].time <= t2 && w >= query[i].weight) {
                    DSU.join(edge[id].u, edge[id].v, true);
                }
            }

            ans.emplace_back(query[i].time, DSU.getSize(query[i].start));
            DSU.rollback();
        }
    }


    sort(begin(ans), end(ans));
    for (auto& i : ans) {
        cout << i.second << "\n";
    }

    return 0;
}

Compilation message

bridges.cpp: In function 'int main()':
bridges.cpp:136:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0, j = 0; i < query.size(); i++) { // O(BLOCK) iterations
                                ~~^~~~~~~~~~~~~~
bridges.cpp:137:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             while (j < unchanged.size() && unchanged[j].weight >= query[i].weight) {
                    ~~^~~~~~~~~~~~~~~~~~

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 348 KB Output is correct
2 Correct 2 ms 256 KB Output is correct
3 Correct 38 ms 504 KB Output is correct
4 Correct 7 ms 628 KB Output is correct
5 Correct 19 ms 504 KB Output is correct
6 Correct 17 ms 504 KB Output is correct
7 Correct 20 ms 504 KB Output is correct
8 Correct 20 ms 504 KB Output is correct
9 Correct 22 ms 476 KB Output is correct
10 Correct 21 ms 504 KB Output is correct
11 Correct 21 ms 508 KB Output is correct
12 Correct 24 ms 504 KB Output is correct
13 Correct 29 ms 504 KB Output is correct
14 Correct 27 ms 504 KB Output is correct
15 Correct 23 ms 504 KB Output is correct
16 Correct 21 ms 504 KB Output is correct
17 Correct 21 ms 504 KB Output is correct

Subtask #2
16.0 / 16.0

# Verdict Execution time Memory Grader output
1 Correct 1474 ms 3852 KB Output is correct
2 Correct 1516 ms 3876 KB Output is correct
3 Correct 1517 ms 3888 KB Output is correct
4 Correct 1584 ms 3888 KB Output is correct
5 Correct 1565 ms 3828 KB Output is correct
6 Correct 2378 ms 4088 KB Output is correct
7 Correct 2377 ms 4084 KB Output is correct
8 Correct 2377 ms 4156 KB Output is correct
9 Correct 49 ms 1508 KB Output is correct
10 Correct 1281 ms 4012 KB Output is correct
11 Correct 1206 ms 3916 KB Output is correct
12 Correct 1237 ms 4488 KB Output is correct
13 Correct 1517 ms 3544 KB Output is correct

Subtask #3
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 1151 ms 2688 KB Output is correct
2 Correct 850 ms 1536 KB Output is correct
3 Correct 1359 ms 2688 KB Output is correct
4 Correct 1127 ms 2700 KB Output is correct
5 Correct 50 ms 1508 KB Output is correct
6 Correct 1292 ms 2748 KB Output is correct
7 Correct 1052 ms 2672 KB Output is correct
8 Correct 938 ms 2652 KB Output is correct
9 Correct 727 ms 3164 KB Output is correct
10 Correct 669 ms 3160 KB Output is correct
11 Correct 855 ms 2324 KB Output is correct
12 Correct 753 ms 2392 KB Output is correct

Subtask #4
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 1701 ms 7148 KB Output is correct
2 Correct 51 ms 1512 KB Output is correct
3 Correct 202 ms 5292 KB Output is correct
4 Correct 122 ms 5184 KB Output is correct
5 Correct 1016 ms 7276 KB Output is correct
6 Correct 1674 ms 7124 KB Output is correct
7 Correct 1006 ms 7440 KB Output is correct
8 Correct 862 ms 4384 KB Output is correct
9 Correct 857 ms 4300 KB Output is correct
10 Correct 866 ms 4236 KB Output is correct
11 Correct 1294 ms 6172 KB Output is correct
12 Correct 1273 ms 6248 KB Output is correct
13 Correct 1315 ms 6376 KB Output is correct
14 Correct 952 ms 7284 KB Output is correct
15 Correct 992 ms 7272 KB Output is correct
16 Correct 1694 ms 7208 KB Output is correct
17 Correct 1720 ms 7120 KB Output is correct
18 Correct 1703 ms 7144 KB Output is correct
19 Correct 1692 ms 7128 KB Output is correct
20 Correct 1458 ms 6768 KB Output is correct
21 Correct 1462 ms 6768 KB Output is correct
22 Correct 1637 ms 7244 KB Output is correct
23 Correct 1014 ms 6836 KB Output is correct

Subtask #5
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 1474 ms 3852 KB Output is correct
2 Correct 1516 ms 3876 KB Output is correct
3 Correct 1517 ms 3888 KB Output is correct
4 Correct 1584 ms 3888 KB Output is correct
5 Correct 1565 ms 3828 KB Output is correct
6 Correct 2378 ms 4088 KB Output is correct
7 Correct 2377 ms 4084 KB Output is correct
8 Correct 2377 ms 4156 KB Output is correct
9 Correct 49 ms 1508 KB Output is correct
10 Correct 1281 ms 4012 KB Output is correct
11 Correct 1206 ms 3916 KB Output is correct
12 Correct 1237 ms 4488 KB Output is correct
13 Correct 1517 ms 3544 KB Output is correct
14 Correct 1151 ms 2688 KB Output is correct
15 Correct 850 ms 1536 KB Output is correct
16 Correct 1359 ms 2688 KB Output is correct
17 Correct 1127 ms 2700 KB Output is correct
18 Correct 50 ms 1508 KB Output is correct
19 Correct 1292 ms 2748 KB Output is correct
20 Correct 1052 ms 2672 KB Output is correct
21 Correct 938 ms 2652 KB Output is correct
22 Correct 727 ms 3164 KB Output is correct
23 Correct 669 ms 3160 KB Output is correct
24 Correct 855 ms 2324 KB Output is correct
25 Correct 753 ms 2392 KB Output is correct
26 Correct 1462 ms 3944 KB Output is correct
27 Correct 1933 ms 4116 KB Output is correct
28 Correct 1639 ms 4000 KB Output is correct
29 Correct 1204 ms 3888 KB Output is correct
30 Correct 1885 ms 3996 KB Output is correct
31 Correct 1907 ms 4004 KB Output is correct
32 Correct 1979 ms 3932 KB Output is correct
33 Correct 1593 ms 3884 KB Output is correct
34 Correct 1606 ms 3960 KB Output is correct
35 Correct 1614 ms 3884 KB Output is correct
36 Correct 1242 ms 3900 KB Output is correct
37 Correct 1243 ms 3880 KB Output is correct
38 Correct 1216 ms 3836 KB Output is correct
39 Correct 1008 ms 4296 KB Output is correct
40 Correct 985 ms 4300 KB Output is correct
41 Correct 1010 ms 4324 KB Output is correct
42 Correct 1054 ms 3656 KB Output is correct
43 Correct 1111 ms 3624 KB Output is correct
44 Correct 1049 ms 3492 KB Output is correct

Subtask #6
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 348 KB Output is correct
2 Correct 2 ms 256 KB Output is correct
3 Correct 38 ms 504 KB Output is correct
4 Correct 7 ms 628 KB Output is correct
5 Correct 19 ms 504 KB Output is correct
6 Correct 17 ms 504 KB Output is correct
7 Correct 20 ms 504 KB Output is correct
8 Correct 20 ms 504 KB Output is correct
9 Correct 22 ms 476 KB Output is correct
10 Correct 21 ms 504 KB Output is correct
11 Correct 21 ms 508 KB Output is correct
12 Correct 24 ms 504 KB Output is correct
13 Correct 29 ms 504 KB Output is correct
14 Correct 27 ms 504 KB Output is correct
15 Correct 23 ms 504 KB Output is correct
16 Correct 21 ms 504 KB Output is correct
17 Correct 21 ms 504 KB Output is correct
18 Correct 1474 ms 3852 KB Output is correct
19 Correct 1516 ms 3876 KB Output is correct
20 Correct 1517 ms 3888 KB Output is correct
21 Correct 1584 ms 3888 KB Output is correct
22 Correct 1565 ms 3828 KB Output is correct
23 Correct 2378 ms 4088 KB Output is correct
24 Correct 2377 ms 4084 KB Output is correct
25 Correct 2377 ms 4156 KB Output is correct
26 Correct 49 ms 1508 KB Output is correct
27 Correct 1281 ms 4012 KB Output is correct
28 Correct 1206 ms 3916 KB Output is correct
29 Correct 1237 ms 4488 KB Output is correct
30 Correct 1517 ms 3544 KB Output is correct
31 Correct 1151 ms 2688 KB Output is correct
32 Correct 850 ms 1536 KB Output is correct
33 Correct 1359 ms 2688 KB Output is correct
34 Correct 1127 ms 2700 KB Output is correct
35 Correct 50 ms 1508 KB Output is correct
36 Correct 1292 ms 2748 KB Output is correct
37 Correct 1052 ms 2672 KB Output is correct
38 Correct 938 ms 2652 KB Output is correct
39 Correct 727 ms 3164 KB Output is correct
40 Correct 669 ms 3160 KB Output is correct
41 Correct 855 ms 2324 KB Output is correct
42 Correct 753 ms 2392 KB Output is correct
43 Correct 1701 ms 7148 KB Output is correct
44 Correct 51 ms 1512 KB Output is correct
45 Correct 202 ms 5292 KB Output is correct
46 Correct 122 ms 5184 KB Output is correct
47 Correct 1016 ms 7276 KB Output is correct
48 Correct 1674 ms 7124 KB Output is correct
49 Correct 1006 ms 7440 KB Output is correct
50 Correct 862 ms 4384 KB Output is correct
51 Correct 857 ms 4300 KB Output is correct
52 Correct 866 ms 4236 KB Output is correct
53 Correct 1294 ms 6172 KB Output is correct
54 Correct 1273 ms 6248 KB Output is correct
55 Correct 1315 ms 6376 KB Output is correct
56 Correct 952 ms 7284 KB Output is correct
57 Correct 992 ms 7272 KB Output is correct
58 Correct 1694 ms 7208 KB Output is correct
59 Correct 1720 ms 7120 KB Output is correct
60 Correct 1703 ms 7144 KB Output is correct
61 Correct 1692 ms 7128 KB Output is correct
62 Correct 1458 ms 6768 KB Output is correct
63 Correct 1462 ms 6768 KB Output is correct
64 Correct 1637 ms 7244 KB Output is correct
65 Correct 1014 ms 6836 KB Output is correct
66 Correct 1462 ms 3944 KB Output is correct
67 Correct 1933 ms 4116 KB Output is correct
68 Correct 1639 ms 4000 KB Output is correct
69 Correct 1204 ms 3888 KB Output is correct
70 Correct 1885 ms 3996 KB Output is correct
71 Correct 1907 ms 4004 KB Output is correct
72 Correct 1979 ms 3932 KB Output is correct
73 Correct 1593 ms 3884 KB Output is correct
74 Correct 1606 ms 3960 KB Output is correct
75 Correct 1614 ms 3884 KB Output is correct
76 Correct 1242 ms 3900 KB Output is correct
77 Correct 1243 ms 3880 KB Output is correct
78 Correct 1216 ms 3836 KB Output is correct
79 Correct 1008 ms 4296 KB Output is correct
80 Correct 985 ms 4300 KB Output is correct
81 Correct 1010 ms 4324 KB Output is correct
82 Correct 1054 ms 3656 KB Output is correct
83 Correct 1111 ms 3624 KB Output is correct
84 Correct 1049 ms 3492 KB Output is correct
85 Correct 2359 ms 6364 KB Output is correct
86 Correct 248 ms 5184 KB Output is correct
87 Correct 168 ms 5308 KB Output is correct
88 Correct 1639 ms 6448 KB Output is correct
89 Correct 2342 ms 6464 KB Output is correct
90 Correct 1635 ms 6496 KB Output is correct
91 Correct 1684 ms 3988 KB Output is correct
92 Correct 1692 ms 3856 KB Output is correct
93 Correct 2468 ms 4056 KB Output is correct
94 Correct 2070 ms 5412 KB Output is correct
95 Correct 2029 ms 5480 KB Output is correct
96 Correct 2301 ms 5552 KB Output is correct
97 Correct 1142 ms 7152 KB Output is correct
98 Correct 1459 ms 5904 KB Output is correct
99 Correct 2405 ms 6396 KB Output is correct
100 Correct 2489 ms 6320 KB Output is correct
101 Correct 2427 ms 6428 KB Output is correct
102 Correct 2421 ms 6400 KB Output is correct
103 Correct 2481 ms 5984 KB Output is correct
104 Correct 2472 ms 6112 KB Output is correct
105 Correct 2083 ms 5304 KB Output is correct
106 Correct 1735 ms 4944 KB Output is correct
107 Correct 1648 ms 6808 KB Output is correct
108 Correct 2496 ms 6388 KB Output is correct
109 Correct 1830 ms 5808 KB Output is correct