【BestCoder】 HDOJ 5103 RootedTree
G++会TLE。。。C++才能AC。。。效率有点低。。。后来去学了更高效的算法。。。。dp代表答案。。sum代表合法的森林。。。
第一次程序：
#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 200005
#define maxm 1000005
#define eps 1e-10
#define mod 1000000007
#define INF 999999999
#define PI (acos(-1.0))
#define lowbit(x) (x&(-x))
#define mp make_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid
#define rson o<<1 | 1, mid+1, R
#pragma comment(linker, "/STACK:16777216")
typedef long long LL;
typedef unsigned long long ULL;
//typedef int LL;
using namespace std;
LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}
// head
int f[1 << 15][15], sum[1 << 15];
int l[15], r[15];
int n;
void read(void)
{
scanf("%d", &n);
for(int i = 1; i <= n; i++) scanf("%d%d", &l[i], &r[i]);
}
void work(void)
{
int tt = (1 << n) - 1;
for(int i = 0; i <= tt; i++) {
sum[i] = 0;
for(int j = 1; j <= n; j++) f[i][j] = 0;
}
for(int i = 0; i <= tt; i++) {
int s = 0, first, last;
for(int j = 1; j <= n; j++)
if(i & (1 << j - 1)) {
s++;
last = j;
if(s == 1) first = j;
}
if(s == 1) {
if(l[last] == 1) f[i][last] = sum[i] = 1;
continue;
}
for(int j = 1; j <= n; j++) {
if(i & (1 << j - 1)) {
f[i][j] = (f[i][j] + sum[i - (1 << j - 1)]) % mod;
int x;
if(j == last) x = first;
else x = last;
int t = i - (1 << j - 1) - (1 << x - 1);
for(int k = t; k; k = (k - 1) & t)
f[i][j] = (f[i][j] + (LL)f[k + (1 << j - 1)][j] * sum[i - k - (1 << j - 1)] % mod) % mod;
if(s >= l[j] && s <= r[j]) sum[i] = (sum[i] + f[i][j]) % mod;
}
}
}
printf("%d\n", sum[tt]);
}
int main(void)
{
int _;
while(scanf("%d", &_)!=EOF) {
while(_--) {
read();
work();
}
}
return 0;
}
第二次程序：
#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 1005
#define maxm 100005
#define eps 1e-10
#define mod 1000000007
#define INF 0x3f3f3f3f
#define PI (acos(-1.0))
#define lowbit(x) (x&(-x))
#define mp make_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid
#define rson o<<1 | 1, mid+1, R
#pragma comment(linker, "/STACK:16777216")
typedef long long LL;
typedef unsigned long long ULL;
//typedef int LL;
using namespace std;
LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}
// head
LL dp[1 << 15], sum[1 << 15];
int l[15], r[15];
int n;
void init(void)
{
memset(dp, 0, sizeof dp);
memset(sum, 0, sizeof sum);
}
void read(void)
{
scanf("%d", &n);
for(int i = 1; i <= n; i++) scanf("%d%d", &l[i], &r[i]);
}
void work(void)
{
sum[0] = 1;
for(int i = 1; i < (1 << n); i++) {
int s = 0, last, first;
for(int j = 1; j <= n; j++)
if(1 & (i >> j - 1)) {
s++;
last = j;
if(s == 1) first = j;
}
if(s == 1) {
if(l[last] == 1) dp[i] = sum[i] = 1;
continue;
}
int x = first;
for(int j = 1; j <= n; j++)
if(1 & (i >> j - 1)) {
if(s >= l[j] && s <= r[j]) dp[i] = (dp[i] + sum[i - (1 << j - 1)]) % mod;
}
sum[i] = (sum[i] + dp[(1 << x - 1)] * sum[i - (1 << x - 1)] % mod) % mod;
int t = i - (1 << x - 1);
for(int j = t; j; j = (j - 1) & t) {
sum[i] = (sum[i] + dp[(1 << x - 1) + j] * sum[i - j - (1 << x - 1)] % mod) % mod;
}
}
printf("%I64d\n", dp[(1 << n) -1]);
}
int main(void)
{
int _;
while(scanf("%d", &_)!=EOF) {
while(_--) {
init();
read();
work();
}
}
return 0;
}