Files
Compsys-2021-Assignments/A1/id_query_binsort.c
Nikolaj 8f39ccb72c 🐛
2021-10-07 14:50:32 +02:00

73 lines
1.8 KiB
C

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <stdint.h>
#include <errno.h>
#include <assert.h>
#include <stdbool.h>
#include "record.h"
#include "id_query.h"
struct index_record {
int64_t osm_id;
const struct record* record;
};
struct indexed_data {
struct index_record* irs;
int n;
};
int comp_func(const void* a, const void* b) {
return (
((struct index_record*)a)->osm_id > ((struct index_record*)b)->osm_id
);
}
struct indexed_data* mk_indexed(struct record* rs, int n) {
struct index_record irs[n];
for (int i = 0 ; i < n ; i++) {
struct record* rec = &rs[i];
struct index_record irec = { .osm_id = rec->osm_id, .record = rec };
irs[i] = irec;
}
struct indexed_data* data = malloc(sizeof(struct indexed_data*));
qsort(&irs, n, sizeof(struct index_record), comp_func);
data->irs = irs;
data->n = n;
return data;
}
void free_indexed(struct indexed_data* data) {
free(data);
}
const struct record* lookup_indexed(struct indexed_data *data, int64_t needle) {
int bottom = 0;
int top = data->n;
int mid;
while (top >= bottom) {
mid = bottom + ((top - bottom) / 2);
if ((&data->irs[mid])->osm_id < needle) {
bottom = mid + 1;
}
else if ((&data->irs[mid])->osm_id > needle) {
top = mid - 1;
}
else if ((&data->irs[mid])->osm_id == needle) {
return (&data->irs[mid])->record;
}
}
return NULL;
}
int main(int argc, char** argv) {
return id_query_loop(argc, argv,
(mk_index_fn)mk_indexed,
(free_index_fn)free_indexed,
(lookup_fn)lookup_indexed);
}