dict3.c

//
// Name : Joowon Byun
// Date : Jung 7th 2016
//
//
#include <stdio.h>
unsigned int combi[201][101];

inline unsigned composition(int n, int r) {
  int i;
  int result = n;

  if (r < 0 || n < 0)
    return 0;
  else if (r > n)
    return 0;
  else if (r == 0 || r == n)
    return 1;
  
  if ( r * 2 > n)
    r = n - r; //reduce by half
  for (i = 2; i <= r; ++i) {
    result *= (n-i+1);
    result /= i;
  }

  return result;
}

void dict(int As, int Bs, int nth) {
  int i, totalHalf;

  if (nth == 1) {
    for (i = 0; i < As; i++)
      printf("a");
    for (i = 0; i < Bs; i++)
      printf("b");

    printf("\n");
    return;
  }

  totalHalf = combi[As + Bs - 1][Bs];
  if (nth <= totalHalf) {
    printf("a");
    dict(As-1, Bs, nth);
  }
  else {
    printf("b");
    dict(As, Bs-1, nth - totalHalf);
  }
}

int main() {
  int numcases, As, Bs, nth, i, j;

  for (i = 0; i <= 200; i++) {
    for (j = 0; j <= 100; j++)
      combi[i][j] = composition(i, j);
  }

  for (i = 0; i <= 200; i++) {
    for (j = 0; j <= 100; j++)
      printf("%u ", combi[i][j]);
    printf("\n");
  }
  
  scanf("%d", &numcases);

  while(numcases--) {
    scanf("%d %d %d", &As, &Bs, &nth);

    if(combi[As + Bs][Bs] < nth)
      printf("NONE\n");
    else
      dict(As, Bs, nth);
  }
  
  return 0;
}