2021ICPC网络赛第一场 :G Longest Prefix Matching 字典树

最新推荐文章于 2025-04-27 23:34:38 发布

原创最新推荐文章于 2025-04-27 23:34:38 发布 · 220 阅读

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分析

看起来是个字典树的板子题？写了个巨丑的代码交上去 $t$ 了，果然人丑常数大

代码

#pragma GCC optimize(3)
#include <bits/stdc++.h>
#define debug(x) cout<<#x<<":"<<x<<endl;
#define dl(x) printf("%lld\n",x);
#define di(x) printf("%d\n",x);
#define _CRT_SECURE_NO_WARNINGS
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> PII;
typedef vector<int> VI;
const int INF = 0x3f3f3f3f;
const int N = 8e5 + 10;
const ll mod = 1000000007;
const double eps = 1e-9;
const double PI = acos(-1);
template<typename T>inline void read(T &a) {
    char c = getchar(); T x = 0, f = 1; while (!isdigit(c)) {if (c == '-')f = -1; c = getchar();}
    while (isdigit(c)) {x = (x << 1) + (x << 3) + c - '0'; c = getchar();} a = f * x;
}
int gcd(int a, int b) {return (b > 0) ? gcd(b, a % b) : a;}
int tr[N][2];
int root[N];
int idx;
int n,m;
int ans;
int a[N][4];
int p[4];

void insert(ull val,int x,int id){
    int p = 0;
    int num = 0;
    for(int i = 31;~i;i--){
        int b = (val >> i) & 1;
        if(!tr[p][b]) tr[p][b] = ++idx;
        p = tr[p][b];
        num++;
        if(num >= x) root[p] = id;
    }
}

void query(ull val){
    int p = 0;
    for(int i = 31;~i;i--){
        int b = (val >> i) & 1;
        if(!tr[p][b]) return;
        p = tr[p][b];
        if(root[p]) ans = root[p];
    }
}

int main() {
    read(n);
    int back;
    for(int i = 1;i <= n;i++){  
        int x;
        scanf("%d.%d.%d.%d",&p[0],&p[1],&p[2],&p[3]);
        ull res = 0;
        for(int j = 0;j < 4;j++){
            ull sum = 0;
            for(int k = 7;~k;k--){
                sum = sum * 2 + (ull)((p[j] >> k) & 1);
            }
            res = res * 256 + sum;
        }
        scanf("%d",&x);
        insert(res,x,i);
        scanf("%d.%d.%d.%d",&a[i][0],&a[i][1],&a[i][2],&a[i][3]);
        if(!x) back = i;
    }
    read(m);
    for(int pppp = 1;pppp <= m;pppp++){
        scanf("%d.%d.%d.%d",&p[0],&p[1],&p[2],&p[3]);
        ull res = 0;
        for(int j = 0;j < 4;j++){
            ull sum = 0;
            for(int k = 7;~k;k--){
                sum = sum * 2 + (ull)((p[j] >> k) & 1);
            }
            res = res * 256 + sum;
        }
        ans = back;
        query(res);
        printf("%d.%d.%d.%d",a[ans][0],a[ans][1],a[ans][2],a[ans][3]);
        if(pppp != m) puts("");
    }
    return 0;
}