Codeforces 463E Caisa and Tree

Caisa and Tree

在dfs的过程中枚举质因子瞎搞搞就好啦， 不过这个题意真的表述不清。。

#include<bits/stdc++.h>
#define LL long long
#define fi first
#define se second
#define mk make_pair
#define PLL pair<LL, LL>
#define PLI pair<LL, int>
#define PII pair<int, int>
#define SZ(x) ((int)x.size())
#define ull unsigned long long
using namespace std;

const int N = 1e5 + 7;
const int M = 2e6 + 7;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e6 + 3;
const double eps = 1e-8;

int n, q, a[N], ans[N], depth[N];
bool prime[M];
vector<int> pfac[M];
vector<PII> Set[M];
vector<int> G[N];

void dfs(int u, int fa) {
    depth[u] = depth[fa] + 1;
    ans[u] = -1;
    for(auto& t : pfac[a[u]])
        if(SZ(Set[t]) && (ans[u] == -1 || Set[t][SZ(Set[t])-1].fi > depth[ans[u]]))
            ans[u] = Set[t][SZ(Set[t])-1].se;
    for(auto& t : pfac[a[u]])
        Set[t].push_back(mk(depth[u], u));
    for(auto& v : G[u]) {
        if(v == fa) continue;
        dfs(v, u);
    }
    for(auto& t : pfac[a[u]])
        Set[t].pop_back();
}

int main() {
    memset(prime, true, sizeof(prime));
    prime[0] = prime[1] = false;
    for(int i = 2; i < M; i++) {
        if(!prime[i]) continue;
        pfac[i].push_back(i);
        for(int j = i + i; j < M; j += i)
            prime[j] = false, pfac[j].push_back(i);
    }
    scanf("%d%d", &n, &q);
    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);
        G[u].push_back(v);
        G[v].push_back(u);
    }
    dfs(1, 0);
    while(q--) {
        int op, v, w;
        scanf("%d%d", &op, &v);
        if(op == 1) {
            printf("%d\n", ans[v]);
        } else {
            scanf("%d", &w);
            a[v] = w;
            dfs(1, 0);
        }
    }
    return 0;
}

/*
*/