做题记录整理图论3 P1600 [NOIP2016 提高组] 天天爱跑步（2022/10/4）

P1600 [NOIP2016 提高组] 天天爱跑步

题解
由于这位大佬似乎afo（？）了，所以我没搞懂那个桶怎么处理，到时候要回来再看一遍

#include <bits/stdc++.h>
#define for1(i,a,b) for(int i = a;i<=b;i++)
#define ll long long
#define mp(a,b) make_pair(a,b)
using namespace std;
int n, m, cnt, hd[300005], dep[300005], fa[300005][23], w[300005];
int cnt1, cnt2, hd1[300005], hd2[300005];
struct node {
    int to;
    int nex;
} a1[300005 * 2], a2[300005 * 2], a3[300005 * 2];

int b1[700005], b2[700005], ji[300005], dis[300005], s[300005], t[300005], l[300005], ans[300005];
const int inf = 300005;
void add(int x, int y) {
    a1[++cnt].to = y;
    a1[cnt].nex = hd[x];
    hd[x] = cnt;
}

void add1(int x, int y) {
    a2[++cnt1].to = y;
    a2[cnt1].nex = hd1[x];
    hd1[x] = cnt1;
}
void add2(int x, int y) {
    a3[++cnt2].to = y;
    a3[cnt2].nex = hd2[x];
    hd2[x] = cnt2;
}

void dfs1(int x, int fat) {
    fa[x][0] = fat;
    dep[x] = dep[fat] + 1;

    for (int i = 1; (1 << i) <= dep[x]; i++)
        fa[x][i] = fa[fa[x][i - 1]][i - 1];

    for (int i = hd[x]; i; i = a1[i].nex) {
        int y = a1[i].to;

        if (y == fat)
            continue;

        dfs1(y, x);
    }
}

int gl(int x, int y) {
    if (x == y)
        return x;

    if (dep[x] < dep[y])
        swap(x, y);

    for (int i = 21; i >= 0; i--)
        if (dep[fa[x][i]] >= dep[y])
            x = fa[x][i];

    if (x == y)
        return x;

    for (int i = 21; i >= 0; i--)
        if (fa[x][i] != fa[y][i])
            x = fa[x][i], y = fa[y][i];

    return fa[x][0];
}


void dfs2(int x) {
    int t1 = b1[w[x] + dep[x]], t2 = b2[w[x] - dep[x] + inf];

    for (int i = hd[x]; i; i = a1[i].nex) {
        int y = a1[i].to;

        if (y == fa[x][0])
            continue;

        dfs2(y);
    }

    b1[dep[x]] += ji[x];

    for (int i = hd1[x]; i; i = a2[i].nex) {
        int y = a2[i].to;
        b2[dis[y] - dep[t[y]] + inf]++;
    }

    ans[x] += b1[w[x] + dep[x]] - t1 + b2[w[x] - dep[x] + inf] - t2;

    for (int i = hd2[x]; i; i = a3[i].nex) {
        int y = a3[i].to;
        b1[dep[s[y]]]--;
        b2[dis[y] - dep[t[y]] + inf]--;
    }
}

int main() {
    scanf("%d%d", &n, &m);
    int x, y;
    for1(i, 1, n - 1) {
        scanf("%d%d", &x, &y);
        add(x, y);
        add(y, x);
    }
    dep[1] = 1;
    fa[1][0] = 1;
    dfs1(1, 0);
    for1(i, 1, n) scanf("%d", &w[i]);
    for1(i, 1, m) {
        scanf("%d%d", &s[i], &t[i]);
        int lca = gl(s[i], t[i]);
        dis[i] = dep[s[i]] + dep[t[i]] - 2 * dep[lca];
        ji[s[i]]++;
        add1(t[i], i);
        add2(lca, i);

        if (dep[lca] + w[lca] == dep[s[i]])
            ans[lca]--;
    }
    dfs2(1);
    for1(i, 1, n)
    printf("%d ", ans[i]);
    return 0;
}