UVA.580 Critical Mass (递推)

题意分析

水

代码总览

#include <bits/stdc++.h>
#define nmax 50
using namespace std;
int dp[nmax];
void init(){
    dp[0] = 1;
    dp[1] = 2;
    dp[2] = 4;
    for(int i = 3;i<nmax;++i){
        dp[i] = dp[i-1] + dp[i-2] + dp[i-3];
    }
}
int main()
{
    int n;
    init();
    while(scanf("%d",&n) && n){
        int ans = 1<<n;
        printf("%d\n",ans - dp[n]);
    }
    return 0;
}