HDU 5834 Magic boy Bi Luo with his excited tree——树形dp

唯一要注意的就是最大和次大，他们可以在一条树链上，值可以相同

PS：超时超到怀疑人生，最后发现数组开大了

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>using namespace std;const int maxn = 1e5 + 10;inline int read() {    int s = 0;    char ch = getchar();    for(; ch < '0' || ch > '9'; ch = getchar());    for(; ch >= '0' && ch <= '9'; ch = getchar()) s = s * 10 + ch - '0';    return s;}int T, n, tot, head[maxn], val[maxn], id[maxn], son[maxn][3], ans[maxn];struct Edge {    int to, cost, next;}edge[maxn<<1];inline void init() {    tot = 0;    memset(head, -1, sizeof(head));}inline void addedge(int u, int v, int cost) {    ++tot;    edge[tot].to = v, edge[tot].cost = cost, edge[tot].next = head[u];    head[u] = tot;}void dfs1(int u, int p) {    for (int i = head[u]; i != -1; i = edge[i].next) {        int v = edge[i].to, cost = edge[i].cost;        if (v == p) continue;        dfs1(v, u);        son[u][0] += max(0, son[v][0] - 2 * cost);    }    for (int i = head[u]; ~i; i = edge[i].next) {        int v = edge[i].to, cost = edge[i].cost;        if (v == p) continue;        int temp = son[u][0] - max(0, son[v][0] - 2 * cost) + max(0, son[v][1] - cost);        if (son[u][1] <= temp) {            son[u][2] = son[u][1];            son[u][1] = temp;            id[u] = v;        }        else if (son[u][2] < temp) son[u][2] = temp;    }}void dfs2(int u, int p, int x, int y) {    ans[u] = max(son[u][1] + x, son[u][0] + y);    for (int i = head[u]; i != -1; i = edge[i].next) {        int v = edge[i].to, cost = edge[i].cost;        if (v == p) continue;        int t0 = son[u][0] - max(0, son[v][0] - 2 * cost);        int xx = max(0, x + t0 - 2 * cost);        int t1;        if (v == id[u]) t1 = son[u][2] - max(0, son[v][0] - 2 * cost);        else t1 = son[u][1] - max(0, son[v][0] - 2 * cost);        int yy = max(0, max(x + t1, y + t0) - cost);        dfs2(v, u, xx, yy);    }}int main() {    T = read();    for (int kase = 1; kase <= T; kase++) {        n = read();        init();        int u, v, cost;        for (int i = 1; i <= n; i++) scanf("%d", &val[i]);        for (int i = 1; i <= n - 1; i++) {            u = read(); v = read(), cost = read();            addedge(u, v, cost); addedge(v, u, cost);        }        memset(id, -1, sizeof(id));        for (int i = 1; i <= n; i++) {            son[i][0] = son[i][1] = son[i][2] = val[i];        }        dfs1(1, -1);        dfs2(1, -1, 0, 0);        printf("Case #%d:\n", kase);        for (int i = 1; i <= n; i++) printf("%d\n", ans[i]);    }    return 0;}