Submission #341385

#	Time	Username	Problem	Language	Result	Execution time	Memory
341385		phathnv	Chase (CEOI17_chase)	C++11	100 / 100	492 ms	334152 KiB

chase

#include <bits/stdc++.h>

#define mp make_pair
#define X first
#define Y second

using namespace std;

typedef long long ll;
typedef pair <int, int> ii;

const int N = 1e5 + 1;
const int V = 101;
const ll INF = 1e18;

int n, k, a[N];
vector <int> adj[N];

ll s[N], dp0[N][V][2], dp1[N][V][2], res[N];

void readInput(){
    scanf("%d %d", &n, &k);
    for(int i = 1; i <= n; i++)
        scanf("%d", &a[i]);
    for(int i = 1; i < n; i++){
        int u, v;
        scanf("%d %d", &u, &v);
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
}

void maximize(ll &x, const ll &y){
    if (x < y)
        x = y;
}

void dfs(int u, int p){
    for(int v : adj[u])
        if (v != p){
            s[u] += a[v];
            s[v] += a[u];
            dfs(v, u);
        }

    for(int i = 0; i <= k; i++)
        for(int mask = 0; mask < 2; mask++)
            dp0[u][i][mask] = dp1[u][i][mask] = -INF;
    for(int i = 0; i <= k; i++){
        dp0[u][i][0] = dp1[u][i][0] = 0;
        if (i > 0)
            dp0[u][i][1] = dp1[u][i][1] = s[u];
    }

    for(int v : adj[u])
        if (v != p){
            for(int i = 0; i <= k; i++){
                maximize(res[u], dp0[u][i][0] + dp1[v][k - i][0]);
                maximize(res[u], dp0[u][i][1] + dp1[v][k - i][0]);
                maximize(res[u], dp0[u][i][0] + dp1[v][k - i][1] - a[u]);
                maximize(res[u], dp0[u][i][1] + dp1[v][k - i][1] - a[u]);

                maximize(res[u], dp1[u][i][0] + dp0[v][k - i][0]);
                maximize(res[u], dp1[u][i][1] + dp0[v][k - i][0] - a[v]);
                maximize(res[u], dp1[u][i][0] + dp0[v][k - i][1]);
                maximize(res[u], dp1[u][i][1] + dp0[v][k - i][1] - a[v]);
            }

            for(int i = 0; i <= k; i++){
                maximize(dp0[u][i][0], dp0[v][i][0]);
                maximize(dp0[u][i][0], dp0[v][i][1]);
                maximize(dp1[u][i][0], dp1[v][i][0]);
                maximize(dp1[u][i][0], dp1[v][i][1] - a[u]);

                if (i > 0){
                    maximize(dp0[u][i][1], dp0[v][i - 1][0] + s[u] - a[v]);
                    maximize(dp0[u][i][1], dp0[v][i - 1][1] + s[u] - a[v]);
                    maximize(dp1[u][i][1], dp1[v][i - 1][0] + s[u]);
                    maximize(dp1[u][i][1], dp1[v][i - 1][1] + s[u] - a[u]);
                }
            }
        }

    maximize(res[u], dp0[u][k][0]);
    maximize(res[u], dp0[u][k][1]);
    maximize(res[u], dp1[u][k][0]);
    maximize(res[u], dp1[u][k][1]);
}

void solve(){
    if (k == 0){
        printf("0");
        return;
    }
    dfs(1, -1);

    printf("%I64lld", *max_element(res + 1, res + 1 + n));
}

int main(){
    readInput();
    solve();
    return 0;
}

Compilation message (stderr)

chase.cpp: In function 'void readInput()':
chase.cpp:22:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   22 |     scanf("%d %d", &n, &k);
      |     ~~~~~^~~~~~~~~~~~~~~~~
chase.cpp:24:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   24 |         scanf("%d", &a[i]);
      |         ~~~~~^~~~~~~~~~~~~
chase.cpp:27:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   27 |         scanf("%d %d", &u, &v);
      |         ~~~~~^~~~~~~~~~~~~~~~~

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