P1352 没有上司的舞会

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

const int MAXn = 6000;
const int NEGINF = 0xc0c0c0c0;

int n;
int d[MAXn + 10][2];
int v[MAXn + 10];

int edgenum;
int head[MAXn + 10];
int next[MAXn + 10];
int to[MAXn + 10];

inline int read(){
    register char c;
    for (c = getchar(); (c < '0' || c>'9') && c != '-'; c = getchar());
    register bool f = c == '-';
    register int s = f ? 0 : c - '0';
    for (c = getchar(); c >= '0' && c <= '9'; c = getchar())s = (s << 3) + (s << 1) + c - '0';
    return f ? -s : s;
}

void first(){
    memset(d, 0xc0c0, sizeof(d));
}

void insert_edge(int from, int too){
    next[++edgenum] = head[from];
    head[from] = edgenum;

    to[edgenum] = too;
}

void put_in(){
    n = read();
    for (int i = 1; i <= n; i++)	
        v[i] = read();
    for (int i = 1; i < n; i++){
        int to = read();
        int from = read();
        insert_edge(from, to);
    }
}

int dp(int nodeid, bool have_root){
    if (d[nodeid][have_root] != NEGINF)	
        return d[nodeid][have_root];
    int& ans = d[nodeid][have_root] = 0;
    if (!have_root)
        for (int i = head[nodeid]; i; i = next[i])
            ans += max(dp(to[i], 0), dp(to[i], 1));
    else{
        ans += v[nodeid];
        for (int i = head[nodeid]; i; i = next[i])
            ans += dp(to[i], 0);
    }
    return ans;
}

int find_root(){
    bool have_in_deg[MAXn + 10] = { 0 };
    for (int i = 1; i <= edgenum; i++)	have_in_deg[to[i]] = 1;
    for (int i = 1; i <= n; i++)
        if (!have_in_deg[i])
            return i;
}

int main(){
    first();
    put_in();
    int rootid = find_root();
    cout << max(dp(rootid, 0), dp(rootid, 1)) << endl;
}

P2015 二叉苹果树

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#include<bits/stdc++.h>
using namespace std;
const int MAXn = 100;
const int MAXq = 100;
const int INF = 0x3f3f3f3f;

int n, q;
int d[MAXn + 10][MAXq + 10];
int to[MAXn + 10][2];//ϱê1ΪfromµÄid
int edgew[MAXn + 10][2];//ϱê1ΪfromµÄid

inline int read(){
    char c;
    while (c = getchar(), c < '0' || c>'9');
    int x(c - '0');
    while (c = getchar(), c >= '0' && c <= '9') x = x * 10 + c - '0';
    return x;
}

void Init(){
    memset(d, -1, sizeof(d));
}

void insert_edge(int nodeid1, int nodeid2, int edge_w){
    if (!to[nodeid1][0]){
        to[nodeid1][0] = nodeid2;
        edgew[nodeid1][0] = edge_w;
        to[nodeid1][0] = nodeid2;
        edgew[nodeid1][0] = edge_w;
    }else{
        to[nodeid1][1] = nodeid2;
        edgew[nodeid1][1] = edge_w;
    }
}

int dp(int nodeid, int keepnum){
    if (d[nodeid][keepnum] != -1)	
        return d[nodeid][keepnum];
    int& ans = d[nodeid][keepnum] = 0;
    if (!keepnum)	
        return ans = 0;
    if (!to[nodeid][0])	
        return ans = -INF;
    for (int knuml = 0; knuml <= keepnum; knuml++){
        int knumr = keepnum - knuml;
        int tmp_ans = 0;
        if (knuml)
            tmp_ans += edgew[nodeid][0] + dp(to[nodeid][0], knuml - 1);
        if (knumr)
            tmp_ans += edgew[nodeid][1] + dp(to[nodeid][1], knumr - 1);
        ans = max(ans, tmp_ans);
    }
    return ans;
}

int main(){
    Init();
    n = read();
    q = read();
    for (int i = 1; i < n; i++){
        int nodeid1 = read();
        int nodeid2 = read();
        int edgew = read();
        insert_edge(nodeid1, nodeid2, edgew);
    }
    cout << dp(1, q);
}