【HDU - 5845】Best Division（xor-trie、01字典树、dp）

#include <cstdio>
#include <algorithm>
#include <cstring>
#define M 268435456
#define N 100005

using namespace std;
int dp[N], a[N];

struct Trie{
    int ch[N*28][2];
    int val[N*28];//异或到当前位置不超过x的最多区间数
    int cnt[N*28];//出现次数
    int size;
    void init(){
        size=0;
        memset(ch,0,sizeof ch);
    }
    void Insert(int node, int pos, int id, int num){
        cnt[node]++;
        if(pos<0){
            val[node]=dp[id];
            return;
        }
        int bit=(num>>pos)&1;
        if(ch[node][bit]==0){
            ch[node][bit]=++size;
            val[size]=-1;
            cnt[size]=0;
        }
        Insert(ch[node][bit], pos-1, id, num);
        val[node]=max(val[node], val[ch[node][bit]]);
    }

    int Query(int node, int pos, int x, int num){
        if(pos<0)
            return val[node];
        int xbit=(x>>pos)&1, nbit=(num>>pos)&1;
        int ans=-1;
        if(xbit){
            if(ch[node][nbit])
                ans = val[ch[node][nbit]];
            if(ch[node][!nbit])
                ans = max(ans, Query(ch[node][!nbit], pos-1, x, num));
        }
        else if(ch[node][nbit])
            ans = Query(ch[node][nbit], pos-1, x, num);
        return ans;
    }

    void Delete(int node, int pos, int num){
        if(!--cnt[node])
            val[node]=-1;
        if(pos<0)
            return;

        int bit=(num>>pos)&1;
        Delete(ch[node][bit], pos-1, num);
        val[node]=val[ch[node][bit]];
        if(ch[node][!bit])
            val[node]=max(val[node],val[ch[node][!bit]]);
    }
}trie;

int main(){
    int t;
    scanf("%d", &t);
    while(t--){
        int n,x,l;
        scanf("%d%d%d", &n,&x,&l);
        int p,q;
        scanf("%d%d%d", &a[1],&p,&q);
        for(int i=2;i<=n;++i)
            a[i]=(a[i-1]*p+q)%M;
        for(int i=2;i<=n;++i)a[i]^=a[i-1];

        trie.init();trie.Insert(0,27,0,0);

        for(int i=1;i<=n;++i){
            if(i>l+1&&dp[i-l-1]!=-1)trie.Delete(0, 27, a[i-l-1]);
            dp[i]=trie.Query(0, 27, x, a[i]);
            if(dp[i]!=-1){
                dp[i]++;
                trie.Insert(0, 27, i, a[i]);
            }
        }
        printf("%d\n", dp[n]==-1?0:dp[n]);
    }
    return 0;
}