OJ-Problems-Source/HDOJ/3553_autoAC.cpp

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#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#define MAXN 100000
#define MAXM 128
int head[MAXN], succ[MAXN], succRank[MAXN];
int sa[MAXN], rank[MAXN];
int letter[MAXM];
void da(char* str, int len) {
memset(letter, 0, sizeof(letter));
for (int i = 0; i < len; ++i)
if (!letter[str[i]])
letter[str[i]] = 1;
int total = -1;
for (int i = 0; i < MAXM; ++i)
if (letter[i])
letter[i] = ++total;
memset(head, 255, sizeof(head));
for (int i = len - 1; i >= 0; --i) {
rank[i] = letter[str[i]];
succ[i] = head[rank[i]];
head[rank[i]] = i;
}
int j = 0;
for (int i = 0; i < len; ++i) {
while (head[j] == -1) ++j;
sa[i] = head[j];
head[j] = succ[head[j]];
}
for (int k = 1; k < len; k <<= 1) {
for (int i = len - 1; i >= 0; --i)
if (sa[i] - k >= 0) {
succRank[sa[i] - k] = rank[sa[i]];
succ[sa[i] - k] = head[rank[sa[i] - k]];
head[rank[sa[i] - k]] = sa[i] - k;
}
for (int i = len - 1; i >= len - k; --i) {
succRank[i] = -1;
succ[i] = head[rank[i]];
head[rank[i]] = i;
}
j = 0; total = -1;
int preSuccRank = 0, preRank = 0;
for (int i = 0; i < len; ++i) {
while (head[j] == -1) ++j;
sa[i] = head[j];
if (i == 0 || preRank != rank[sa[i]] || preSuccRank != succRank[sa[i]]) {
preRank = rank[sa[i]];
rank[sa[i]] = ++total;
} else {
preRank = rank[sa[i]];
rank[sa[i]] = total;
}
preSuccRank = succRank[sa[i]];
head[j] = succ[head[j]];
}
}
}
int height[MAXN];
long long mem[MAXN + 1], *sumLength = mem + 1;
void calcHeight(char* str, int len) {
int i, j, k = 0;
for (i = 0; i < len; ++i) {
if (k != 0)
--k;
if (rank[i] == 0)
continue;
j = sa[rank[i] - 1];
while (str[i + k] == str[j + k])
++k;
height[rank[i]] = k;
}
}
int minData[MAXN + 1][18];
inline int minHeight(int x, int y) {
return height[x] <= height[y] ? x : y;
}
inline void initRMQ(int s, int e) {
if (s > e)
return;
for (int i = s; i <= e; ++i)
minData[i][0] = i;
int h = (int)(log(e - s + 1.0) / log(2.0));
for (int j = 1; j <= h; ++j)
for (int i = s; i + (1 << j) - 1 <= e; ++i)
minData[i][j] = minHeight(minData[i][j - 1], minData[i + (1 << (j - 1))][j - 1]);
}
inline int askRMQ(int a, int b) {
int l = (int)(log(b - a + 1.0) / log(2.0));
return minHeight(minData[a][l], minData[b - (1 << l) + 1][l]);
}
inline int lcp(int a, int b) {
return height[askRMQ(std::min(rank[a], rank[b]) + 1, std::max(rank[a], rank[b]))];
}
char buf[MAXN + 2];
long long k;
int rk, rl;
void getAnswer(long long a, long long b) {
int h = 0;
while (a != b) {
int idx = askRMQ(a + 1, b) - 1;
if (k <= (height[idx + 1] - h) * (b - a + 1)) {
rk = a; rl = h + 1 + (k - 1) / (b - a + 1);
return;
}
k -= (height[idx + 1] - h) * (b - a + 1);
if (k <= sumLength[idx] - sumLength[a - 1] - height[idx + 1] * (idx - a + 1)) {
b = idx; h = height[idx + 1];
continue;
}
k -= sumLength[idx] - sumLength[a - 1] - height[idx + 1] * (idx - a + 1);
a = idx + 1;
h = height[idx + 1];
}
rk = a; rl = h + k;
}
int main() {
int test;
scanf("%d", &test);
for (int cas = 1; cas <= test; ++cas) {
scanf("%s%I64d", buf, &k);
int len = strlen(buf);
da(buf, len);
calcHeight(buf, len);
for (int i = 0; i < len; ++i)
sumLength[i] = sumLength[i - 1] + len - sa[i];
initRMQ(1, len - 1);
getAnswer(0, len - 1);
printf("Case %d: ", cas);
for (int i = 0; i < rl; ++i)
putchar(buf[sa[rk] + i]);
putchar('\n');
}
return 0;
}