Click here to download priceisright.c.

#include <stdio.h>

int main() {
  int contestants = 4;
  printf("Enter %i guesses: ", contestants);
  fflush(stdout);

  // read in guesses
  double guess[contestants];
  for (int i=0; i < contestants; ++i) {
    scanf(" %lg", &guess[i]);
  }

  printf("True price: ");
  fflush(stdout);
  double actual;
  scanf(" %lg", &actual);

  // find the closest guess
  double closest = -1;
  int winner = -1;
  for (int i=0; i < contestants; ++i) {
    if (guess[i] <= actual && guess[i] > closest) {
      closest = guess[i];
      winner = i + 1; // add one because indexes start at 0
    }
  }

  // print who won
  if (winner < 0) {
    printf("Everyone guessed over!\n");
  } else {
    printf("Contestant %i wins\n", winner);
  }

  return 0;
}