Submission #101555

#	Time	Username	Problem	Language	Result	Execution time	Memory
101555		shenxy	Chase (CEOI17_chase)	C++11	50 / 100	2149 ms	525312 KiB

chase

#include <cstdio>
#include <algorithm>
#include <vector>
using namespace std;
int n, v;
vector<long long int> p;
vector< vector<int> > adjlist;
vector< vector<int> > children;
vector< vector< vector<long long int> > > dptable;
long long int smalldp(int v, int pa, int crumbs) {
    if (dptable[v][pa][crumbs] != -1) return dptable[v][pa][crumbs];
    if (crumbs == 0) return 0;
    long long int ans = 0, maxdp = 0, maxnocrumb = 0;
    for (int i = 0; i < adjlist[v].size(); i++) {
        if (adjlist[v][i] == pa) continue;
        ans += p[adjlist[v][i]];
        maxdp = max(maxdp, smalldp(adjlist[v][i], v, crumbs - 1));
        maxnocrumb = max(maxnocrumb, smalldp(adjlist[v][i], v, crumbs));
    }
    return dptable[v][pa][crumbs] = max(maxdp + ans, maxnocrumb);
}
void roottree(int v, int pa) {
    for (int i = 0; i < adjlist[v].size(); i++) {
        if (adjlist[v][i] != pa) {
            children[v].push_back(adjlist[v][i]);
            roottree(adjlist[v][i], v);
        }
    }
}
long long int bigdp(int v, int crumbs) {
    if (dptable[0][v][crumbs] != -1) return dptable[0][v][crumbs];
    if (crumbs == 0) return 0;
    long long int ans = 0, maxdp = 0, maxnocrumb = 0;
    for (int i = 0; i < children[v].size(); i++) {
        ans += p[children[v][i]];
        maxdp = max(maxdp, bigdp(children[v][i], crumbs - 1));
        maxnocrumb = max(maxnocrumb, bigdp(children[v][i], crumbs));
    }
    return dptable[0][v][crumbs] = max(maxdp + ans, maxnocrumb);
}
int main() {
    scanf("%d %d", &n, &v);
    long long int nextint;
    for (int i = 0; i < n; i++) {
        scanf("%lld", &nextint);
        p.push_back(nextint);
        adjlist.push_back(vector<int>());
    }
    int a, b;
    for (int i = 1; i < n; i++) {
        scanf("%d %d", &a, &b);
        adjlist[a - 1].push_back(b - 1);
        adjlist[b - 1].push_back(a - 1);
    }
    if (n <= 1000) {
        for (int i = 0; i < n; i++) {
            dptable.push_back(vector< vector<long long int> >(n + 1, vector<long long int>(v + 1, -1)));
        }
        long long int ans = 0;
        for (int i = 0; i < n; i++) {
            ans = max(ans, smalldp(i, n, v));
        }
        printf("%lld\n", ans);
        return 0;
    } else {
        for (int i = 0; i < n; i++) {
            children.push_back(vector<int>());
        }
        dptable.push_back(vector< vector<long long int> >(n, vector<long long int>(v + 1, -1)));
        roottree(0, -1);
        printf("%lld", bigdp(0, v));
        return 0;
    }
}

Compilation message (stderr)

chase.cpp: In function 'long long int smalldp(int, int, int)':
chase.cpp:14:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < adjlist[v].size(); i++) {
                     ~~^~~~~~~~~~~~~~~~~~~
chase.cpp: In function 'void roottree(int, int)':
chase.cpp:23:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < adjlist[v].size(); i++) {
                     ~~^~~~~~~~~~~~~~~~~~~
chase.cpp: In function 'long long int bigdp(int, int)':
chase.cpp:34:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < children[v].size(); i++) {
                     ~~^~~~~~~~~~~~~~~~~~~~
chase.cpp: In function 'int main()':
chase.cpp:42:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &v);
     ~~~~~^~~~~~~~~~~~~~~~~
chase.cpp:45:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld", &nextint);
         ~~~~~^~~~~~~~~~~~~~~~~~
chase.cpp:51:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &a, &b);
         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 0 / 20
• Subtask 3: 30 / 30
• Subtask 4: 0 / 30