BZOJ4698: Sdoi2008 Sandy的卡片(二分 hash)

题意

Sol

用什么后缀数组啊

直接差分之后二分+hash找最长公共子串就赢了啊。。。

时间复杂度：\(O(nlogn)\)(不过我写的是两个log。。反正也能过)

// luogu-judger-enable-o2

#include<bits/stdc++.h>

#define ull unsigned long long

using namespace std;

const int MAXN = 1e6 + 10;

const ull base = 27;

inline int read() {

    char c = getchar(); int x = 0, f = 1;

    while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}

    while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();

    return x * f;

}

int N, mx;

ull po[MAXN];

vector<ull> ha[MAXN];

vector<int> v[MAXN];

map<ull, int> mp, vis;

ull getha(int id, int l, int r) {

    if(l == 0) return ha[id][r];

    else return ha[id][r] - ha[id][l - 1] * po[r - l + 1];

}

int check(int len) {

    mp.clear();

    for(int i = 1; i <= N; i++) {

        vis.clear();

        for(int j = 0; j < v[i].size() - len + 1; j++) {

            ull tmp = getha(i, j, j + len - 1);

            if(!vis[tmp]) vis[tmp] = 1, mp[tmp]++;

            if(mp[tmp] == N) return 1;

        }

    }

    return 0;

}

int main() {

    N = read();

    po[0] = 1;

    for(int i = 1; i <= 10001; i++) po[i] = base * po[i - 1];

    for(int i = 1; i <= N; i++) {

        int num = read(); mx = max(mx, num);

        for(int j = 1; j <= num; j++) v[i].push_back(read());

        for(int j = num - 1; j >= 1; j--) v[i][j] = v[i][j] - v[i][j - 1];

        ha[i].reserve(v[i].size() + 1);

    }

    for(int i = 1; i <= N; i++) {

        for(int j = 0; j < v[i].size(); j++) {

            if(!j) ha[i][j] = 0;

            else ha[i][j] = (ha[i][j - 1] + v[i][j]) * base;

        }

    }

    int l = 1, r = mx, ans = 0;

    while(l <= r) {

        int mid = l + r >> 1;

        if(check(mid)) ans = mid, l = mid + 1;

        else r = mid - 1;

    }

    cout << ans + 1;

    return 0;

}

巴特西

BZOJ4698: Sdoi2008 Sandy的卡片(二分 hash)

题意

Sol

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