hdu 4691 Front compression（后缀数组）

题目链接：hdu 4691 Front compression

代码

#include 
#include 
#include 

using namespace std;

const int maxn = 1e5 + 5;
typedef long long ll;

struct Suffix_Arr {
    int n, s[maxn];
    int SA[maxn], rank[maxn], height[maxn];
    int tmp_one[maxn], tmp_two[maxn], c[305];

    int d[maxn][20];

    void init(char* str);
    void build(int m);
    void get_height();
    void rmq_init();
    int rmq_query(int x, int y);
}solver;

char str[maxn];

int bitcount(int n) {
    if (n == 0) return 1;
    int ret = 0;
    while (n) {
        n /= 10;
        ret++;
    }
    return ret;
}

int N, L[maxn], R[maxn];
void solve () {
    ll in = 0, ot = 0;
    scanf("%d", &N);
    L[0] = R[0] = solver.n-1;
    for (int i = 1; i <= N; i++) {
        scanf("%d%d", &L[i], &R[i]);
        int l = solver.rank[L[i-1]], r = solver.rank[L[i]];
        int k = min(solver.rmq_query(l, r), min(R[i-1] - L[i-1], R[i] - L[i]));
        int len = R[i] - L[i];

        in += R[i] - L[i];
        ot += len - k + bitcount(k);
    }
    printf("%lld %lld\n", in + N, ot + 2 * N);
}

int main () {
    while (scanf("%s", str) == 1) {
        solver.init(str);
        solver.build(300);
        solver.get_height();
        solver.rmq_init();
        solve();
    }
    return 0;
}

void Suffix_Arr::init(char* str) {
    n = 0;
    int len = strlen(str);
    for (int i = 0; i < len; i++)
        s[n++] = str[i] - 'a' + 1;
    s[n++] = 0;
}

void Suffix_Arr::rmq_init() {
    for (int i = 0; i < n; i++) d[i][0] = height[i];

    for (int k = 1; (1<for (int i = 0; i + (1<1 < n; i++)
            d[i][k] = min(d[i][k-1], d[i+(1<<(k-1))][k-1]);
    }
}

int Suffix_Arr::rmq_query(int x, int y) {
    if (x == y) return n - SA[x];

    if (x > y) swap(x, y);

    x++;
    int k = 0;
    while ((1<<(k+1)) <= y - x + 1) k++;
    return min(d[x][k], d[y-(1<1][k]);
}

void Suffix_Arr::get_height() {
    for (int i = 0; i < n; i++) rank[SA[i]] = i;

    int mv = height[0] = 0;

    for (int i = 0; i < n - 1; i++) {
        if (mv) mv--;

        int j = SA[rank[i]-1];
        while (s[i+mv] == s[j+mv]) mv++;
        height[rank[i]] = mv;
    }
}

void Suffix_Arr::build(int m) {
    int *x = tmp_one, *y = tmp_two;

    for (int i = 0; i < m; i++) c[i] = 0;
    for (int i = 0; i < n; i++) c[x[i] = s[i]]++;
    for (int i = 1; i < m; i++) c[i] += c[i-1];
    for (int i = n-1; i >= 0; i--) SA[--c[x[i]]] = i;

    for (int k = 1; k <= n; k <<= 1) {

        int mv = 0;
        for (int i = n-k; i < n; i++) y[mv++] = i;
        for (int i = 0; i < n; i++) if (SA[i] >= k)
            y[mv++] = SA[i] - k;

        for (int i = 0; i < m; i++) c[i] = 0;
        for (int i = 0; i < n; i++) c[x[y[i]]]++;
        for (int i = 1; i < m; i++) c[i] += c[i-1];
        for (int i = n-1; i >= 0; i--) SA[--c[x[y[i]]]] = y[i];

        swap(x, y);
        mv = 1;
        x[SA[0]] = 0;

        for (int i = 1; i < n; i++)
            x[SA[i]] = (y[SA[i-1]] == y[SA[i]] && y[SA[i-1] + k] == y[SA[i] + k] ? mv-1 : mv++);

        if (mv >= n) break;
        m = mv;
    }
}