#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <time.h>
#include <unistd.h>

#define NONE -1

enum { SORT_DESC = 0, SORT_ASC };
enum { UNSORTED = 0, SORT_WR, SORT_VR, SORT_RW, SORT_RV};

static int debug;
static int sort;
static int sort_order;

typedef struct _InputItem
{
   int i;               /* item index */
   int v;               /* item value */
   int w;               /* item weight */
} InputItem;

typedef struct _SolverItem {
     int i;             /* index of the selected item */
     int v;             /* cumulated value */
     int w;             /* cumulated weight */
} SolverItem;

typedef struct _Solver
{
   int k;               /* capacity */
   int n;               /* items # */
   int w_sum;           /* sum of input items weight */
   InputItem *items;    /* items */
   SolverItem *column;  /* solver column */
} Solver;

static int
item_cmp(const void *p1, const void *p2)
{
   int ret;
   float r1, r2;
   const InputItem *i1, *i2;

   i1 = (const InputItem *) p1;
   i2 = (const InputItem *) p2;

   ret = ((sort_order == SORT_ASC) ? 1 : -1);

   if (sort == SORT_WR)
     {
        if (i1->w > i2->w) return  ret;
        if (i1->w < i2->w) return -ret;
     }
   else if (sort == SORT_VR)
     {
        if (i1->v > i2->v) return  ret;
        if (i1->v < i2->v) return -ret;
     }
   else  // SORT_RW | SORT_RV
     {
        r1 = i1->v / (float)i1->w;
        r2 = i2->v / (float)i2->w;
        if (r1 > r2) return  ret;
        if (r1 < r2) return -ret;
     }

   if (sort == SORT_RW)
     {
        if (i1->w > i2->w) return  ret;
        if (i1->w < i2->w) return -ret;
     }
   else if (sort == SORT_RV)
     {
        if (i1->v > i2->v) return  ret;
        if (i1->v < i2->v) return -ret;
     }
   else  // SORT_WR | SORT_VR
     {
        r1 = i1->v / (float)i1->w;
        r2 = i2->v / (float)i2->w;
        if (r1 > r2) return  ret;
        if (r1 < r2) return -ret;
     }

   return 0;
}

static void solve(Solver* solver)
{
   int n, k;
   int v, w;
   int i, j;
   int min_c, lower_bound;
   const InputItem *item;
   SolverItem *data;
   const SolverItem *up_left;

   unsigned int counter;

   n = solver->n;
   k = solver->k;
   min_c = solver->w_sum;

   if (debug > 2)
     {
        printf("\nformat V(i,W)\n");
     }

   /* SOLVE */
   counter = 0;
   item = solver->items;
   for (i = 0; i < n; i++, item++)
     {
        v = item->v;
        w = item->w;
        data = solver->column + solver->k;
        up_left = solver->column + (solver->k - w);

        // this computes the top-left bottom-right diagonal,
        // values above this don't need to be computed
        min_c -= w;
        lower_bound = (k - min_c);
        if (lower_bound < w)
          lower_bound = w;
        for (j = k; j >= lower_bound; j--, data--, up_left--)
          {
             counter++;

             if (data->v < (v + up_left->v))
               {
                  data->i = i;
                  data->v = v + up_left->v;
                  data->w = w + up_left->w;
               }
          }

        if (debug > 2)
          {
             printf("i=%d; j=k; j<=%d:\n", i, lower_bound);
             data = solver->column;
             for (j = 0; j <= k; j++, data++)
               printf("  %d : % 4d(% 2d % 2d)\n",
                      j, data->v, data->i, data->w);
             printf("\n");
          }
     }

   if (debug == 2)
     {
        printf("i=%d:\n", solver->n - 1);
        data = solver->column;
        for (j = 0; j <= k; j++, data++)
          printf("  % 4d(% 2d % 2d)\n",
                 data->v, data->i, data->w);
     }

   if (debug > 0)
     printf("loops count: %u\n", counter);
}

static int check(Solver *solver, int excpected_value)
{
   const SolverItem *data;

   if (excpected_value == NONE)
     return EXIT_SUCCESS;

   data = solver->column + solver->k;
   if (data->v != excpected_value)
     {
        fprintf(stderr,"*** ERROR found %d != %d excpected !",
                data->v, excpected_value);
        return EXIT_FAILURE;
     }

     return EXIT_SUCCESS;
}

int main(int argc, char** argv, char** env)
{
   FILE *fp;

   int ret;
   int opt;
   int i;
   int excpected_value;
   uint64_t dt;
   struct timespec t0;
   struct timespec t1;

   Solver solver;
   InputItem *item;

   debug = 0;
   sort = UNSORTED;
   sort_order = SORT_DESC;
   excpected_value = NONE;
   while ((opt = getopt(argc, argv, "d:e:s:S")) != -1) {
        switch (opt) {
           case 'd':
              debug = atoi(optarg);
              break;
           case 'e':
              excpected_value = atoi(optarg);
              break;
           case 's':
              sort = atoi(optarg);
              break;
           case 'S':
              sort_order = SORT_ASC;
              break;
           default: /* '?' */
              fprintf(stderr, "Usage: %s [falgs] input\n",
                      argv[0]);
              return EXIT_FAILURE;
        }
   }

   if (optind >= argc) {
        fprintf(stderr,"input file missing\n");
        return EXIT_FAILURE;
   }

   if (sort > SORT_RV) sort = UNSORTED;
   if (sort_order > SORT_ASC) sort = SORT_DESC;

   if (debug > 0) printf("%s\n", argv[optind]);
   fp = fopen(argv[optind], "r");
   if (fp == NULL)
     {
        fprintf(stderr, "I couldn't open results.dat for reading.\n");
        return EXIT_FAILURE;
     }

   /* read k and n */
   if (fscanf(fp, "%d %d\n", &solver.n, &solver.k) != 2)
     {
        fprintf(stderr, "ERROR: read first line\n");
        return EXIT_FAILURE;
     }
   if (debug > 0) printf("  K:%d N:%d\n", solver.k, solver.n);

   /* allocate */
   solver.items = calloc(solver.n, sizeof(InputItem));
   if (!solver.items)
     {
        fprintf(stderr, "ERROR: items calloc\n");
        return EXIT_FAILURE;
     }

   solver.column = calloc((solver.k + 1), sizeof(SolverItem));
   if (!solver.column)
     {
        free(solver.items);
        fprintf(stderr, "ERROR: column calloc\n");
        return EXIT_FAILURE;
     }
   for (i = 0; i < (solver.k + 1); i++)
     {
        solver.column[i].i = NONE;
     }

   /* read items */
   solver.w_sum = 0;
   item = solver.items;
   for (i = 0; i < solver.n; i++, item++)
     {
        item->i = i;
        fscanf(fp, "%d %d\n", &item->v, &item->w);
        solver.w_sum += item->w;
     }
   fclose(fp);

   if (sort != UNSORTED)
     qsort(solver.items, solver.n, sizeof(InputItem), item_cmp);

   if (debug > 1)
     {
        printf("  Items ");
        if (sort == UNSORTED)
          {
              printf("unsorted\n");
          }
        else
          {
             printf("sorted ");
             switch(sort){
                  case SORT_VR:
                     printf("Value,ratio(V/W)");
                     break;
                  case SORT_WR:
                     printf("Weight,ratio(V/W)");
                     break;
                  case SORT_RW:
                     printf("ratio(V/W),Weight");
                     break;
                  case SORT_RV:
                     printf("ratio(V/W),Value");
                     break;
                  default:
                     break;
             }
            if (sort_order == SORT_ASC)
              printf(" asc\n");
            else
              printf(" desc\n");
          }
        item = solver.items;
        printf("     index    Value   Weight (sum %d)\n", solver.w_sum);
        for (i = 0; i < solver.n; i++, item++)
          printf("  % 8d % 8d % 8d\n", item->i, item->v, item->w);
     }

   clock_gettime(CLOCK_MONOTONIC, &t0);
   solve(&solver);
   clock_gettime(CLOCK_MONOTONIC, &t1);

   ret = check(&solver, excpected_value);

   if (debug > 0)
     {
        dt = ((t1.tv_sec * 1000000000) + t1.tv_nsec) -
           ((t0.tv_sec * 1000000000) + t0.tv_nsec);
        printf(" time %7u [ms]\n", (unsigned int)(dt/1000000));
     }

   free(solver.items);
   free(solver.column);

   return ret;
}