(Relax 后缀数组1.3)POJ 3415 Common Substrings(求串A和串B中长度不小于k的公共子串数)

#include <iostream>#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>#include <string>#define Fup(i, s, t) for (int i = s; i <= t; i ++)#define Fdn(i, s, t) for (int i = s; i >= t; i --)#define Path(i, s) for (int i = s; i; i = d[i].next)using namespace std;const int maxn = 200010;struct number {int x;int pos;} num[maxn];struct node {int now;int next;} d[maxn];int val[maxn][2];int c[maxn];int rank[maxn];int sa[maxn];int pos[maxn];int x[maxn];int n;int k;int h[maxn];int height[maxn];string S,s;int sta[maxn], num1[maxn], num2[maxn];bool cmp(const number& a, const number& b) {return a.x < b.x;}void add_value(int u, int v, int i) {d[i].next = c[u];c[u] = i;d[i].now = v;}void radix_sort(int l, int r) {for (int k = 1; k >= 0; --k) {memset(c, 0, sizeof(c));for (int i = r; i >= l; --i) {add_value(val[pos[i]][k], pos[i], i);}int t = 0;for (int i = 0; i <= 200000; ++i) {for (int j = c[i]; j; j = d[j].next) {pos[++t] = d[j].now;}}}int t = 0;for (int i = 1; i <= n; ++i) {if (val[pos[i]][0] != val[pos[i - 1]][0]|| val[pos[i]][1] != val[pos[i - 1]][1]) {t++;}rank[pos[i]] = t;}}bool exist(int len) {int now = 0;int s = 0;for (int i = 1; i <= n; ++i) { //枚举名次数组...if (height[i] < len) {s = max(s, now); //结束当前组now = 1; //now恢复为1} else {now++;}}s = max(s, now);if (s >= k) {return 1;}return 0;}void get_suffix_array() {int t = 1;while (t / 2 <= n) {for (int i = 1; i <= n; ++i) {val[i][0] = rank[i];val[i][1] = (((i + t / 2 <= n) ? rank[i + t / 2] : 0));pos[i] = i;}radix_sort(1, n);t *= 2;}for (int i = 1; i <= n; ++i) {sa[rank[i]] = i;}}void get_common_prefix() {memset(h, 0, sizeof(h));for (int i = 1; i <= n; ++i) {if (rank[i] == 1) {h[i] = 0;} else {int now = 0;if (i > 1 && h[i - 1] > 1) {now = h[i - 1] - 1;}while (now + i <= n && now + sa[rank[i] - 1] <= n&& x[now + i] == x[now + sa[rank[i] - 1]]) {now++;}h[i] = now;}}for (int i = 1; i <= n; ++i) {height[rank[i]] = h[i];}}int binary_search(int l, int r) {while (l <= r) {int mid = (l + r) / 2;if (exist(mid)) {l = mid + 1;} else {r = mid - 1;}}return r;}void get_ans() {Fup(i, 2, n)height[i] -= k - 1;long long sum1 = 0, sum2 = 0, ans = 0;int top = 0;Fup(i, 2, n)if (height[i] <= 0) {top = sum1 = sum2 = 0;} else {sta[++top] = height[i];if (sa[i - 1] <= (int) S.size()) {num1[top] = 1;num2[top] = 0;sum1 += (long long) sta[top];} else {num1[top] = 0;num2[top] = 1;sum2 += (long long) sta[top];}while (top > 0 && sta[top] <= sta[top - 1]) {sum1 = sum1 - (long long) sta[top - 1] * num1[top - 1]+ (long long) sta[top] * num1[top - 1];sum2 = sum2 - (long long) sta[top - 1] * num2[top - 1]+ (long long) sta[top] * num2[top - 1];num1[top - 1] += num1[top];num2[top - 1] += num2[top];sta[top - 1] = sta[top];top--;}if (sa[i] <= (int) S.size())ans += sum2;elseans += sum1;}cout << ans << endl;}void init() {cin >> S >> s;n = (int) S.size() + s.size() + 1;string str = S + '$' + s;Fup(i, 1, n)x[i] = rank[i] = (int) str[i - 1];}void solve() {get_suffix_array();get_common_prefix();get_ans();}int main(){while(scanf("%d",&k)!=EOF,k){init();solve();}return 0;}