CCF NOI100003 up the stairs __noi100003

question link : CCF NOI100003 up the stairs .

Time limit: 1000 ms Space limit: 262144 KB

Topic Description

Stairs have n steps, stairs can be a step up the stairs, can also step two steps. Compile a program to calculate how many different walks are in total.

input

One row, an integer n (1 <= n <= 30), represents the series of steps .

Output

An integer, the number of methods to go.

Sample Input

3
Sample Output

3
Programme 1: Walk three times, one step at a time
Scenario 2: Go first, then two.
Option 3: Go to Level Two first, go again

Data Range Restrictions

Problem Analysis

This is a recursive computation problem, the key is to find the recursive type.

See the reference link.

Program Description

Slightly

Essentials to use functions to encapsulate functional functions as far as possible. The key to recursion problem is recursion type.

Reference link : HDU2041 super Staircase.

The C language Program of 100 minutes:

#include <stdio.h>

typedef unsigned long long ull;

ull Stairs (int n)
{
    ull f1=1, f2=2, temp;

    if (n = = 0) return
        0;
    else if (n = = 1) return
        1;
    else if (n = = 2) return
        2;

    for (int i=3; i<=n; i++) {
        temp = f1 + F2;
        f1 = F2;
        F2 = temp;
    }

    return f2;
}

int main (void)
{
    int n;

    scanf ("%d", &n);

    printf ("%lld\n", Stairs (n));

    return 0;
}