Submission #76626

#	Time	Username	Problem	Language	Result	Execution time	Memory
76626		alexpetrescu	Dreaming (IOI13_dreaming)	C++14	100 / 100	179 ms	13328 KiB

dreaming

#include "dreaming.h"

#include <vector>

#define MAXN 100000

struct myc {
    int x, y;
};

std::vector < myc > g[MAXN];
int ans, best, t[MAXN], opa[MAXN], ops[MAXN], cine[MAXN];
bool viz[MAXN];

void dfs1(int x) {
    viz[x] = 1;
    for (auto &y : g[x]) {
        if (viz[y.x] == 0) {
            t[y.x] = x;
            dfs1(y.x);
            if (opa[y.x] + y.y > opa[x]) {
                ops[x] = opa[x];
                opa[x] = opa[y.x] + y.y;
                cine[x] = y.x;
            } else if (opa[y.x] + y.y > ops[x])
                ops[x] = opa[y.x] + y.y;
        }
    }
}

void dfs2(int x, int sus) {
    int cat = std::max(opa[x], sus);
    if (cat > ans)
        ans = cat;
    if (best == -1 || cat < best)
        best = cat;
    for (auto &y : g[x]) {
        if (t[y.x] == x) {
            if (y.x == cine[x])
                dfs2(y.x, y.y + std::max(sus, ops[x]));
            else
                dfs2(y.x, y.y + std::max(sus, opa[x]));
        }
    }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    for (int i = 0; i < M; i++) {
        g[A[i]].push_back({B[i], T[i]});
        g[B[i]].push_back({A[i], T[i]});
    }

    ans = 0;
    int max1 = -1, max2 = -1, max3 = -1;
    for (int i = 0; i < N; i++) {
        if (viz[i] == 0) {
            dfs1(i);
            best = -1;
            dfs2(i, 0);
            if (best > max1) {
                max3 = max2;
                max2 = max1;
                max1 = best;
            } else if (best > max2) {
                max3 = max2;
                max2 = best;
            } else if (best > max3)
                max3 = best;
        }
    }

    if (max2 != -1)
        ans = std::max(ans, max1 + max2 + L);
    if (max3 != -1)
        ans = std::max(ans, max2 + max3 + 2 * L);

    return ans;
}

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 18 / 18
• Subtask 5: 12 / 12
• Subtask 6: 23 / 23