标签:style http color os io for ar 代码
题意:给定n个数字,每个数字可以是0-l,要选其中一些数字,然后使得和为k,问方案
思路:状压dp,滚动数组,状态表示第i个数字,能组成的数字状态为s的状态,然后每次一个数字,循环枚举它要选取1 - min(l,k)的多少,然后进行状态转移
代码:
#include <cstdio> #include <cstring> typedef long long ll; const int N = (1<<20) + 5; const ll MOD = 1000000007; int t, n, k; ll l, dp[N]; int main() { scanf("%d", &t); while (t--) { scanf("%d%d%lld", &n, &k, &l); int s = (1<<k); ll yu = l - k; l = k; memset(dp, 0, sizeof(dp)); dp[0] = 1; while (n--) { for (int i = s - 1; i >= 0; i--) { if (dp[i] == 0) continue; ll tmp = yu * dp[i] % MOD; ll now = dp[i]; for (int j = 1; j <= l; j++) { int next = i|((i<<j)&(s - 1)|(1<<(j - 1))); dp[next] = (dp[next] + now) % MOD; } dp[i] = (dp[i] + tmp) % MOD; } } ll ans = 0; for (int i = 0; i < s; i++) { if (i&(1<<(k - 1))) { ans = (ans + dp[i]) % MOD; } } printf("%lld\n", ans); } return 0; }
HDU 4906 Our happy ending (状压DP),布布扣,bubuko.com
HDU 4906 Our happy ending (状压DP)
标签:style http color os io for ar 代码
原文地址:http://blog.csdn.net/accelerator_/article/details/38326841