Fibonacci Number

fibo.c

int fibo(int);
int fibo(int N) {
  if (0 == N) return 0;
  if (1 == N || 2 == N) return 1;
  int pre = 1, cur = 1;
  for (int i = 3; i <= N; ++i) {
    int sum = pre + cur;
    pre = cur;
    cur = sum;
  }
  return cur;
}