Submission #915840

#	Time	Username	Problem	Language	Result	Execution time	Memory
915840		vjudge1	Palindromic Partitions (CEOI17_palindromic)	C11	Compilation error	0 ms	0 KiB

palindromic

// Greedy solution with rolling string hashes. Repeatedly takes the smallest possible
// chunk from the sides, using string hashes to quickly check for equality of chunks.
// Hash updating and comparison takes O(1), so the total running time is O(n).

#include <algorithm>
#include <cstring>
#include "assert.h"
#include "stdio.h"

#define MAX_WORD_LENGTH 5100000

int longest_palindromic_partition(char *word) {
	const int n = strlen(word);
	const unsigned int base = 131;
	int done_chars = 0;
	int n_chunks = 0;
	while (done_chars * 2 < n) {
		unsigned int left_hash=0, right_hash=0;
		unsigned int base_power=1;
		for (int chunk_size=1; true; chunk_size++) {
			const int l = done_chars;
			const int r = n - done_chars - chunk_size;
			if (l + chunk_size - 1 >= r) {
				return n_chunks + 1;
			}
			base_power = chunk_size == 1 ? 1 : base_power * base;
			left_hash += static_cast<unsigned int>(word[l + chunk_size - 1]) * base_power;
			right_hash = static_cast<unsigned int>(word[r]) + right_hash * base;
			if (left_hash == right_hash && strncmp(word + l, word + r, chunk_size) == 0) {
				n_chunks += 2;
				done_chars += chunk_size;
				break;
			}
		}
	}
	return n_chunks;
}

int main() {
	int n;
	char word[MAX_WORD_LENGTH];
	scanf("%d\n", &n);	
	for (int i=0; i<n; i++) {
		scanf("%s\n", word);
		assert(strlen(word) <= MAX_WORD_LENGTH);
		printf("%d\n", longest_palindromic_partition(word));
	}
	return 0;
}

Compilation message (stderr)

palindromic.c:5:10: fatal error: algorithm: No such file or directory
    5 | #include <algorithm>
      |          ^~~~~~~~~~~
compilation terminated.