bnu36907 Subpalindromes 字符串hash+线段树

标签：线段树   hash   

bnu36907 Subpalindromes

字符串hash+线段树

题意：给一个字符串（<=1e5）, 进行操作和查询(<=1e5）。

1）将指定位置的字符改为c

2）询问l-r的子串，是否是回文串。

解法 ：区间维护pl和pr，表示从左到右的hash和从右到左的hash，然后在up和query中合并区间，最后判断pl和pr是否相等即可。

#include <cstdio>
#include <ctime>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <string>
#include <set>
#include <stack>
#include <map>
#include <cmath>
#include <vector>
#include <iostream>
#include <algorithm>
#include <bitset>
#include <fstream>
using namespace std;
//LOOP
#define FF(i, a, b) for(int i = (a); i < (b); ++i)
#define FE(i, a, b) for(int i = (a); i <= (b); ++i)
#define FED(i, b, a) for(int i = (b); i>= (a); --i)
#define REP(i, N) for(int i = 0; i < (N); ++i)
#define CLR(A,value) memset(A,value,sizeof(A))
#define FC(it, c) for(__typeof((c).begin()) it = (c).begin(); it != (c).end(); it++)
//OTHER
#define SZ(V) (int)V.size()
#define PB push_back
#define MP make_pair
#define all(x) (x).begin(),(x).end()
//INPUT
#define RI(n) scanf("%d", &n)
#define RII(n, m) scanf("%d%d", &n, &m)
#define RIII(n, m, k) scanf("%d%d%d", &n, &m, &k)
#define RIV(n, m, k, p) scanf("%d%d%d%d", &n, &m, &k, &p)
#define RV(n, m, k, p, q) scanf("%d%d%d%d%d", &n, &m, &k, &p, &q)
#define RS(s) scanf("%s", s)

#define sqr(x) (x) * (x)
typedef long long LL;
typedef unsigned long long ULL;
typedef vector <int> VI;
const int INF = 0x3f3f3f3f;
const double EPS = 1e-9;
const int MOD = 1000000007;
const double PI = acos(-1.0);
const int maxn = 100100;
#define ll rt << 1
#define rr rt << 1 | 1

const int SEED = 13331;

ULL P[maxn + 10];
char s[maxn];
void hash_pre(ULL P[])
{
    P[0] = 1;
    for (int i = 1; i <= maxn; i++)
        P[i] = P[i - 1] * SEED;
}
struct HashNode{
    ULL pl, pr;
    HashNode(){}
    HashNode(ULL pl, ULL pr) : pl(pl), pr(pr){}
}qans;
struct Node{
    int l, r, m;
    ULL pl, pr;
}st[maxn << 2];
inline void up(int rt)
{
    st[rt].pl = st[ll].pl * P[st[rt].r - st[rt].m] + st[rr].pl;
    st[rt].pr = st[rr].pr * P[st[rt].m - st[rt].l + 1] + st[ll].pr;
}
void build(int l, int r, int rt)
{
    st[rt].l = l ;st[rt].r = r;
    int m = (l + r) >> 1;
    st[rt].m = m;
    if (l == r)
    {
        st[rt].pl = st[rt].pr = s[l - 1];
        return;
    }
    build(l, m, ll); build(m + 1, r, rr);
    up(rt);
}
void update(int x, char c, int rt)
{
    if (st[rt].l == st[rt].r)
    {
        st[rt].pl = st[rt].pr = c;
        return ;
    }
    if (x <= st[rt].m) update(x, c, ll);
    else update(x, c, rr);
    up(rt);
}
inline HashNode gettmp(HashNode tmp1, HashNode tmp2, int l, int r, int m)
{
    HashNode tmp;
    tmp.pl = tmp1.pl * P[r - m] + tmp2.pl;
    tmp.pr = tmp2.pr * P[m - l + 1] + tmp1.pr;
    return tmp;
}
HashNode query(int L, int R, int rt)
{
    if (L <= st[rt].l && st[rt].r <= R)
    {
        return HashNode(st[rt].pl, st[rt].pr);
    }
    if (R <= st[rt].m) return query(L, R, ll);
    else if (L > st[rt].m) return query(L, R, rr);
    else
    {
        HashNode tmp1 = query(L, R,  ll);
        HashNode tmp2 = query(L, R, rr);
        return gettmp(tmp1, tmp2, max(L, st[rt].l), min(R, st[rt].r), st[rt].m);
    }
}
char ss[110];
int main()
{
    hash_pre(P);
    int n, q;
    while (~RS(s))
    {
        n = strlen(s);
        build(1, n, 1);
        RI(q);
        while (q--)
        {
            RS(ss);
            if (ss[0] == 'c')
            {
                int x; char c;
                RI(x); scanf(" %c", &c);
                update(x, c, 1);
            }
            else
            {
                int x, y;
                RII(x, y);
                qans = query(x, y, 1);
                if (qans.pl == qans.pr) puts("Yes");
                else puts("No");
            }
        }
    }
    return 0;
}

bnu36907 Subpalindromes 字符串hash+线段树,布布扣,bubuko.com

bnu36907 Subpalindromes 字符串hash+线段树

标签：线段树   hash   

原文地址：http://blog.csdn.net/guognib/article/details/38497285