Sha 11107-life forms (suffix array)

Sha 11107-life forms

Question Link

Given some strings, find the longest and appear more than half of the number of consecutive substrings of all strings, and output these strings

Train of Thought: concatenate these strings and splice them with a non-repeated character. Then, find the suffix array of the long string and use the height array for binary solution, if there is a continuous height segment that exceeds half the number of times in the binary judgment, it is feasible. If none of the continuous segments appear more than half, it is not feasible.

Code:

#include <cstdio>#include <cstring>#include <algorithm>#include <set>using namespace std;const int MAXLEN = 200005;struct Suffix {    int s[MAXLEN];    int sa[MAXLEN], t[MAXLEN], t2[MAXLEN], c[MAXLEN], n;    int rank[MAXLEN], height[MAXLEN];    void build_sa(int m) {int i, *x = t, *y = t2;for (i = 0; i < m; i++) c[i] = 0;for (i = 0; i < n; i++) c[x[i] = s[i]]++;for (i = 1; i < m; i++) c[i] += c[i - 1];for (i = n - 1; i >= 0; i--) sa[--c[x[i]]] = i;for (int k = 1; k <= n; k <<= 1) {    int p = 0;    for (i = n - k; i < n; i++) y[p++] = i;    for (i = 0; i < n; i++) if (sa[i] >= k) y[p++] = sa[i] - k;    for (i = 0; i < m; i++) c[i] = 0;    for (i = 0; i < n; i++) c[x[y[i]]]++;    for (i = 0; i < m; i++) c[i] += c[i - 1];    for (i = n - 1; i >= 0; i--) sa[--c[x[y[i]]]] = y[i];    swap(x, y);    p = 1; x[sa[0]] = 0;    for (i = 1; i < n; i++)x[sa[i]] = y[sa[i - 1]] == y[sa[i]] && y[sa[i - 1] + k] == y[sa[i] + k] ? p - 1 : p++;    if (p >= n) break;    m = p;}        }    void getHeight() {int i, j, k = 0;for (i = 0; i < n; i++) rank[sa[i]] = i;for (i = 0; i < n; i++) {    if (k) k--;    if (rank[i] == 0) continue;    int j = sa[rank[i] - 1];    while (s[i + k] == s[j + k]) k++;    height[rank[i]] = k;}    }} gao;const int N = 1005;int n, l, r, id[MAXLEN];char str[N];bool judge(int x, int bo) {    set<int> vis;        vis.insert(id[gao.sa[1]]);    for (int i = 2; i < gao.n; i++) {while (i < gao.n && gao.height[i] >= x) {    vis.insert(id[gao.sa[i]]);    i++;}if (vis.size() * 2 > n) {    if (bo == 0)return true;    for (int j = 0; j < x; j++)printf("%c", gao.s[gao.sa[i - 1] + j]);    printf("\n");}vis.clear();vis.insert(id[gao.sa[i]]);    }    return false;}void solve() {    if (!judge(1, 0)) {printf("?\n");return;    }    l = 1; r++;    while (l < r) {int mid = (l + r) / 2;if (judge(mid, 0)) l = mid + 1;else r = mid;    }    l--;    judge(l, 1);}int main() {    int bo = 0;    while (~scanf("%d", &n) && n) {if (bo) printf("\n");else bo = 1;if (n == 1) {    scanf("%s", str);    printf("%s\n", str);    continue;}int tot = 0;r = 0;for (int i = 0; i < n; i++) {    scanf("%s", str);    int len = strlen(str);    r = max(len, r);    for (int j = 0; j < len; j++) {id[tot] = i;gao.s[tot++] = str[j];    }    id[tot] = i;    gao.s[tot++] = 'z' + i + 1;}gao.n = tot;gao.build_sa('z' + n + 1);gao.getHeight();solve();    }    return 0;}