uva 10934—— Dropping water balloons

题意:给定K个气球,然后n层楼的高度,求确定气球的硬度(站在多高能摔破)


思路:递推。dp(i,j)表示最优,那么即dp(i-1,j-1)+1最优,如果K层没有破,则把K+1看成1层继续。得到转移方程dp(i,j)=k+dp(i,j-1)=dp(i-1,j-1)+dp(i,j-1);


code:

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

const int INF=9999999;
const int inf=-INF;
const int N=125;
const int M=2005;
const int mod=1000000007;
const double pi=acos(-1.0);

#define cls(x,c) memset(x,c,sizeof(x))
#define ft(i,s,n) for (int i=s;i<=n;i++)
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define lrt  rt<<1
#define rrt  rt<<1|1
#define middle int m=(r+l)>>1
#define lowbit(x) (x&-x)
#define pii pair
#define mk make_pair
#define IN freopen("in.txt","r",stdin);
#define OUT freopen("out.txt","w",stdout);

int k,ans;
ll n,dp[N][N];
int main()
{
    while (~scanf("%d%lld",&k,&n),k)
    {
        cls(dp,0);k=min(k,63);ans=-1;
        ft(i,1,63) ft(j,1,63)
            dp[i][j]=dp[i-1][j-1]+1+dp[i][j-1];
        ft(i,1,63)
        if (dp[k][i]>=n) {ans=i;break;}
        if(ans>-1) printf("%d\n",ans);
        else puts("More than 63 trials needed.");
    }
}


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