洛谷P3919_离线dfs

离线操作dfs

#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

ll n,a[(int)1e6+9],m,ans[(int)1e6+9];
std::vector<int> g[(int)1e6+9];
struct opt
{
    int opt,wz,val;
}e[(int)1e6+9];

void dfs(int x){
    auto [aa,bb,cc]=e[x];
    if(aa==2)ans[x]=a[bb];
    else ans[x]=-1;
    if(aa==1){
        ll tmp=a[bb];
        a[bb]=cc;
        for(auto it :g[x])dfs(it);
        a[bb]=tmp;
    }else{
        for(auto it :g[x])dfs(it);
    }
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>n>>m;
    f(i,1,n)cin>>a[i];
    for(int i=1,x,y,z,w;i<=m;++i){
        cin>>x>>y>>z;
        if(y==1){
            cin>>w;
        }
        g[x].push_back(i);
        e[i]={y,z,w};
    }
    dfs(0);
    f(i,1,m)if(~ans[i])cout<<ans[i]<<"\n";
    return 0;
}