hdu 4691 Front compression（后缀数组）

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题目链接：hdu 4691 Front compression
代码

#include <cstdio>#include <cstring>#include <algorithm>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<<k) <= n; k++) {        for (int i = 0; i + (1<<k) - 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<<k)+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;    }}
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