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257 lines (217 loc) · 6.35 KB
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Copy pathweights.c
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257 lines (217 loc) · 6.35 KB
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#define _GNU_SOURCE
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <stdbool.h>
typedef struct Pair {
int weight;
int strength;
} Pair;
typedef struct IntTable {
int *data;
int nrows;
int ncolumns;
} IntTable;
void int_table_fill(IntTable *tbl, int value) {
for (int i = 0; i < tbl->nrows * tbl->ncolumns; i++) {
*(tbl->data + i) = value;
}
}
IntTable *int_table_new(int rows, int columns) {
IntTable *tbl = malloc(sizeof(IntTable));
int *data = malloc(sizeof(int) * rows * columns);
if (tbl == NULL || data == NULL) {
return NULL;
}
tbl->data = data;
tbl->nrows = rows;
tbl->ncolumns = columns;
int_table_fill(tbl, 0);
return tbl;
}
void int_table_free(IntTable *tbl) {
free(tbl->data);
return free(tbl);
}
int *int_table_row(IntTable *tbl, int row) {
if (row >= 0 && row < tbl->nrows) {
return tbl->data + (tbl->ncolumns * row);
} else {
return NULL;
}
}
int int_table_get(IntTable *tbl, int row, int column) {
int *rowptr = int_table_row(tbl, row);
return *(rowptr + column);
}
void int_table_set(IntTable *tbl, int row, int column, int value) {
*(int_table_row(tbl, row) + column) = value;
}
void int_table_print(IntTable *tbl) {
for (int i = 0; i < tbl->nrows; i++) {
for (int k = 0; k < tbl->ncolumns; k++) {
printf("%5i", int_table_get(tbl, i, k));
}
printf("\n");
}
}
static void fill(int *data, int length, int value) {
for (int *p = data; p != data + length; p += 1) {
*p = value;
}
}
static int int_cmp_rev(const void *a, const void *b) {
const int *ia = (const int *)a; // casting pointer types
const int *ib = (const int *)b;
return *ib - *ia;
}
static int find_by_value(int arr[], int length, int value) {
for (int i = 0; i < length; i++) {
if (arr[i] == value) return i;
}
return -1;
}
static bool is_already_used_item(int item_idx, int seq_length, IntTable *parents) {
int idx = item_idx;
while ((idx = int_table_get(parents, seq_length, idx)) != -1) {
if (item_idx == idx) {
//printf("element with index %i already used in parent sequence\n", idx);
return true;
}
seq_length -= 1;
}
// printf("element with index %i is not used in parent sequence\n", item_idx);
return false;
}
int find_parent(int seq_length, int child_idx, IntTable *capacities,
IntTable *parents) {
/* printf("searching for suitable parent element for sequence length: %i\n", */
/* seq_length); */
int caps_sorted[capacities->ncolumns];
memcpy(caps_sorted, int_table_row(capacities, seq_length - 1),
capacities->ncolumns * sizeof(int));
qsort(caps_sorted, capacities->ncolumns, sizeof(int), int_cmp_rev);
for (int i = 0; i < capacities->ncolumns; i++) {
int parent_idx = find_by_value(int_table_row(capacities, seq_length - 1),
capacities->ncolumns, caps_sorted[i]);
/* printf("checking element with index: %i and capacity: %i\n", */
/* parent_idx, caps_sorted[i]); */
if (parent_idx == child_idx) {
continue;
}
if (is_already_used_item(child_idx, seq_length, parents)) {
continue;
} else {
// printf("returning parent index: %i\n", parent_idx);
return parent_idx;
}
}
return -1;
}
/**
Finds min of two integers.
**/
int find_min(int a, int b) {
return a < b ? a : b;
}
/**
Finds maximum of provided int sequence.
Returns: Index of the max element.
**/
int find_max(int *seq, int length) {
int value = INT_MIN;
int value_idx = -1;
for (int i = 0; i < length; i++) {
if (*(seq + i) > value) {
value = *(seq + i);
value_idx = i;
}
}
return value;
}
int find_seq_length(Pair input_data[], int input_length) {
IntTable *lengths = int_table_new(input_length + 1, input_length);
IntTable *capacities = int_table_new(input_length + 1, input_length);
IntTable *parents = int_table_new(input_length + 1, input_length);
int_table_fill(parents, -1);
for (int l = 0; l <= input_length; l++) {
//printf("considering sequence of %i elements:\n", l);
for (int t = 0; t < input_length; t++) {
//printf("\tconsidering sequence ending on element %i:\n", t);
int w = input_data[t].weight;
int s = input_data[t].strength;
if (l == 0) {
int_table_set(parents, l, t, -1);
continue;
} else if (l == 1) {
int_table_set(lengths, l, t, 1);
int_table_set(parents, l, t, -1);
int_table_set(capacities, l, t, s - w);
continue;
}
int_table_set(parents, l, t, find_parent(l, t, capacities, parents));
/* printf("\t\tparent element for (%i; %i): %i\n", l, t, */
/* int_table_get(parents, l, t)); */
if (int_table_get(parents, l, t) == -1) {
int_table_set(lengths, l, t, int_table_get(lengths, l - 1, t));
int_table_set(parents, l, t, -1);
int_table_set(capacities, l, t, 0);
continue;
}
int parent_capacity = int_table_get(capacities, l - 1,
int_table_get(parents, l, t));
int capacity = find_min(s, parent_capacity);
if (capacity - w > 0) {
int_table_set(capacities, l, t, capacity - w);
int_table_set(lengths, l, t, l);
} else {
int_table_set(capacities, l, t, 0);
int_table_set(lengths, l, t, int_table_get(lengths, l-1, t));
int_table_set(parents, l, t, -1);
}
}
}
printf("Lengths table:\n");
int_table_print(lengths);
printf("Parents table:\n");
int_table_print(parents);
printf("Capacities table:\n");
int_table_print(capacities);
int seq_length = find_max(int_table_row(lengths, lengths->nrows - 1),
lengths->ncolumns);
int_table_free(lengths);
int_table_free(capacities);
int_table_free(parents);
return seq_length;
}
int main(int argc, char* argv[]) {
union {
char a[10];
int i;
} a_union;
int *pint = (int*)&a_union;
*pint = 5;
Pair input[5607] = {};
int data = 0, i = 0, input_length = 0;
while (scanf("%i", &data) != EOF) {
if (i % 2 == 0) {
input[input_length].weight = data;
} else {
input[input_length].strength = data;
}
i += 1;
if (i > 1) {
i = 0;
input_length += 1;
}
}
printf("read %i input entities:\n", input_length);
for (int i = 0; i < input_length; i++) {
printf("\tinput %i (weight; strength): %i; %i\n",
i, input[i].weight, input[i].strength);
}
int seq_length = find_seq_length(input, input_length);
printf("longest sequence: %i\n", seq_length);
}