Submission #242305

#	Time	Username	Problem	Language	Result	Execution time	Memory
242305		cheeheng	Magic Tree (CEOI19_magictree)	C++14	48 / 100	2127 ms	794228 KiB

magictree

#include <bits/stdc++.h>
using namespace std;

vector<int> AdjList[100005];

int d[100005];
long long w[100005];
int L[100005];

long long subtreeSum[100005][25];

// subtree rooted at i, day x
void dfs1(int i, int x){
    long long ans = (d[i] == x)*w[i];
    for(int j: AdjList[i]){
        dfs1(j, x);
        ans += subtreeSum[j][x];
    }

    subtreeSum[i][x] = ans;
}

long long memo[100005][1005];

long long dfs2(int i, int k){
    if(k == 0){
        return 0;
    }else if(memo[i][k] != -1){
        return memo[i][k];
    }

    long long ans = 0;
    // delaying for 1 more day is acceptable
    //ans = dfs2(i, k-1);

    long long temp2 = 0;
    for(int j: AdjList[i]){
        // either choose to cut or do not cut
        long long tempVal = dfs2(j, k);
        if(d[j] <= k){
            tempVal = max(tempVal, w[j] + dfs2(j, d[j]));
        }

        temp2 += tempVal;
    }
    ans = max(ans, temp2);

    return memo[i][k] = ans;
}

int main(){
    int n, m, k;
    scanf("%d%d%d", &n, &m, &k);

    bool subtask3 = true;
    for(int i = 2; i <= n; i ++){
        int p;
        scanf("%d", &p);
        subtask3 &= (p == i-1);

        AdjList[p].push_back(i);
    }

    bool subtask2 = true;
    long long ans2 = 0;
    memset(d, -1, sizeof(d));
    vector<int> xingchen;
    for(int i = 1; i <= m; i ++){
        int x, y, z;
        scanf("%d%d%d", &x, &y, &z);
        subtask3 &= (z == 1);
        subtask2 &= AdjList[x].empty();
        d[x] = y;
        w[x] = z;
        ans2 += w[x];
        xingchen.push_back(d[x]);
    }
    sort(xingchen.begin(), xingchen.end());
    xingchen.erase(unique(xingchen.begin(), xingchen.end()), xingchen.end());

    for(int i = 1; i <= n; i ++){
        if(d[i] == -1){continue;}
        d[i] = 1+lower_bound(xingchen.begin(), xingchen.end(), d[i]) - xingchen.begin();
        //printf("d[%d]=%d\n", i, d[i]);
    }

    if(subtask2){
        printf("%lld", ans2);
        return 0;
    }

    if(subtask3){
        int lis = 0;
        /*for(int i = n; i >= 2; i --){
            printf("%d ", d[i]);
        }
        printf("\n");*/
        for(int i = n; i >= 2; i --){
            if(d[i] == -1){continue;}
            int pos = upper_bound(L, L+lis, d[i])-L;
            L[pos] = d[i];
            if(pos == lis){
                lis ++;
            }
        }
        printf("%d\n", lis);
        return 0;
    }else if((int)xingchen.size() <= 1001){
        int K = xingchen.size();
        /*for(int i = 0; i <= k; i ++){
            dfs1(1, i);
        }*/

        memset(memo, -1, sizeof(memo));
        for(int i = 1; i <= n; i ++){
            memo[i][0] = 0;
        }

        for(int k = 1; k <= K; k ++){
            for(int i = n; i >= 1; i --){
                long long temp2 = 0;
                for(int j: AdjList[i]){
                    // either choose to cut or do not cut
                    long long tempVal = memo[j][k];
                    if(d[j] <= k){
                        tempVal = max(tempVal, w[j] + memo[j][d[j]]);
                    }

                    temp2 += tempVal;
                }
                memo[i][k] = temp2;
            }
        }

        printf("%lld\n", memo[1][K]);
        return 0;
    }else{
        throw;
    }

    return 0;
}

Compilation message (stderr)

magictree.cpp: In function 'int main()':
magictree.cpp:53:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d", &n, &m, &k);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~
magictree.cpp:58:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &p);
         ~~~~~^~~~~~~~~~
magictree.cpp:70:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d", &x, &y, &z);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 3 / 3
• Subtask 3: 11 / 11
• Subtask 4: 12 / 12
• Subtask 5: 16 / 16
• Subtask 6: 0 / 13
• Subtask 7: 0 / 22
• Subtask 8: 0 / 17