标签：hdu 5155 harry and magic box
问题描述
dp[i][j] += dp[i][j-1]*(2^i - 1) + dp[i-k][j-1] * c[k][i] * (2^(i-k))
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
typedef __int64 ll;
const int MOD = 1000000007;
const int N = 51;
ll c[N][N],dp[N][N],t[N];
int n,m;
void init() {
memset(c,0,sizeof(c));
c[0][0] = 1;
for (int i = 1;i <= N; i++) {
c[i][0] = 1;
for (int j = 1;j <= i; j++)
c[i][j] = (c[i-1][j-1] + c[i-1][j]) % MOD;
}
t[0] = 1;
for(int i = 1; i <= N; i++) {
t[i] = t[i-1] *2 % MOD;
}
}
int main() {
init();
while(scanf("%d%d",&n,&m) != EOF) {
for(int i = 0; i <= n; i++)
dp[i][1] = 1;
for(int j = 0; j <= m; j++)
dp[1][j] = 1;
for(int i = 2; i <= n; i++) {
for(int j = 2; j <= m; j++) {
dp[i][j] = dp[i][j-1] * (t[i] - 1) % MOD;
for(int k = 1; k < i; k++) {
dp[i][j] = (dp[i][j] + dp[i-k][j-1] * c[i][k] % MOD * t[i-k] % MOD) % MOD;
}
}
}
printf("%I64d\n",dp[n][m]);
}
return 0;
}
HDU - 5155 Harry And Magic Box
标签：hdu 5155 harry and magic box
原文地址：http://blog.csdn.net/helloworld10086/article/details/42456775
