kk Blog —— 通用基础

date [-d @int|str] [+%s|"+%F %T"]

dancing links

Knuth Dancing_Links 中文版 http://www.docin.com/p-31928825.html

http://acm.fzu.edu.cn/problem.php?pid=1686

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=3209

http://acm.hdu.edu.cn/showproblem.php?pid=3529

http://acm.hdu.edu.cn/showproblem.php?pid=3663

http://acm.hdu.edu.cn/showproblem.php?pid=2295

http://poj.org/problem?id=3074

http://poj.org/problem?id=3076

// fzu 1686
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#include<stdio.h>
#include<algorithm>

using namespace std;

const int MAXN = 225;
int L[MAXN*MAXN], R[MAXN*MAXN], U[MAXN*MAXN], D[MAXN*MAXN];
int S[MAXN];
int Col[MAXN*MAXN];
int limit;

void Remove(int x) {
	for (int i = D[x]; i != x; i = D[i]) {
	L[R[i]] = L[i];
	R[L[i]] = R[i];
	}
}
void Resume(int x) {
	for (int i = U[x]; i != x; i = U[i]) {
	L[R[i]] = R[L[i]] = i;
	}
}
int Hash() {
	int ans = 0;
	bool hash[MAXN] = {0};
	for (int c = R[0]; c != 0; c = R[c])
	if (! hash[c]) {
		hash[c] = true;
		ans ++;
		for (int i = D[c]; i != c; i = D[i])
		for (int j = R[i]; j != i; j = R[j])
		hash[Col[j]] = true;
	}
	return ans;
}

bool dfs(int depth) {
	if (depth + Hash() > limit) return false;
	if (R[0] == 0) return true;
	int i, j, c, minnum = INT_MAX;
	for (i = R[0]; i != 0; i = R[i]) {
		if (S[i] < minnum) {
			minnum = S[i];
			c = i;
		}
	}
	for (i = U[c]; i != c; i = U[i]) {
			Remove(i);
			for (j = R[i]; j != i; j = R[j]) Remove(j);
			if (dfs(depth + 1)) {
			for (j = L[i]; j != i; j = L[j]) Resume(j);
			Resume(i);
			return true;
		}
		for (j = L[i]; j != i; j = L[j]) Resume(j);
		Resume(i);
	}
	return false;
}

int solve(int n, int m, int DL[][MAXN], int maxdepth) {
	if (maxdepth > n) maxdepth = n;
	for (int i = 0; i <= m; i ++) {
		L[i] = i - 1;
		R[i] = i + 1;
		U[i] = D[i] = i;
	}
	L[0] = m;
	R[m] = 0;
	int cnt = m + 1;
	memset(S, 0, sizeof (S));
	for (int i = 1; i <= n; i ++) {
		int head = cnt, tail = cnt;
		for (int c = 1; c <= m; c ++) if (DL[i][c]) {
			S[c] ++;
			Col[cnt] = c;
			U[D[c]] = cnt;
			D[cnt] = D[c];
			U[cnt] = c;
			D[c] = cnt;
			L[cnt] = tail;
			R[tail] = cnt;
			R[cnt] = head;
			L[head] = cnt;
			tail = cnt;
			cnt ++;
		}
	}
	int best = 0, worst = maxdepth;
	while (best <= worst) {
		limit = (worst + best) >> 1;
		if (dfs(0)) worst = limit - 1;
		else best = limit + 1;
	}
	return best;
}

int main()
{
	int i,j,k,l,row,col,n,m,n1,m1,mark[MAXN][MAXN],a[33][33],id[33][33];

	while(scanf("%d %d",&n,&m) != EOF)
	{
		col = 0;
		for(i=1;i<=n;i++)
			for(j=1;j<=m;j++)
			{
				scanf("%d",&a[i][j]);
				id[i][j] = -1;
				if(a[i][j] == 1) { col++; id[i][j] = col; }
			}
		scanf("%d %d",&n1,&m1);

		row = 0;
		for(i=1;i<=n-n1+1;i++)
			for(j=1;j<=m-m1+1;j++)
			{
				row++;
				for(k=1;k<=col;k++)mark[row][k] = 0;
			
				for(k=i;k<i+n1;k++)
					for(l=j;l<j+m1;l++)
					if(id[k][l] > 0)
						mark[row][id[k][l]] = 1;
			}
		
		printf("%d\n",solve(row, col, mark, row));
	}
	return 0;
}
// hdu 2295
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#include<stdio.h>
#include<algorithm>
#include<math.h>
#include<string.h>

using namespace std;

const int MAXN = 225;
int L[MAXN*MAXN], R[MAXN*MAXN], U[MAXN*MAXN], D[MAXN*MAXN];
int S[MAXN];
int Col[MAXN*MAXN];
int limit;

void Remove(int x) {
	for (int i = D[x]; i != x; i = D[i]) {
	L[R[i]] = L[i];
	R[L[i]] = R[i];
	}
}
void Resume(int x) {
	for (int i = U[x]; i != x; i = U[i]) {
	L[R[i]] = R[L[i]] = i;
	}
}
int Hash() {
	int ans = 0;
	bool hash[MAXN] = {0};
	for (int c = R[0]; c != 0; c = R[c])
	if (! hash[c]) {
		hash[c] = true;
		ans ++;
		for (int i = D[c]; i != c; i = D[i])
		for (int j = R[i]; j != i; j = R[j])
		hash[Col[j]] = true;
	}
	return ans;
}

bool dfs(int depth) {
	if (depth + Hash() > limit) return false;
	if (R[0] == 0) return true;
	int i, j, c, minnum = 2000000000;
	for (i = R[0]; i != 0; i = R[i]) {
		if (S[i] < minnum) {
			minnum = S[i];
			c = i;
		}
	}
	for (i = U[c]; i != c; i = U[i]) {
			Remove(i);
			for (j = R[i]; j != i; j = R[j]) Remove(j);
			if (dfs(depth + 1)) {
			for (j = L[i]; j != i; j = L[j]) Resume(j);
			Resume(i);
			return true;
		}
		for (j = L[i]; j != i; j = L[j]) Resume(j);
		Resume(i);
	}
	return false;
}

int solve(int n, int m, int DL[][MAXN], int maxdepth) {
	if (maxdepth > n) maxdepth = n;
	for (int i = 0; i <= m; i ++) {
		L[i] = i - 1;
		R[i] = i + 1;
		U[i] = D[i] = i;
	}
	L[0] = m;
	R[m] = 0;
	int cnt = m + 1;
	memset(S, 0, sizeof (S));
	for (int i = 1; i <= n; i ++) {
		int head = cnt, tail = cnt;
		for (int c = 1; c <= m; c ++) if (DL[i][c]) {
			S[c] ++;
			Col[cnt] = c;
			U[D[c]] = cnt;
			D[cnt] = D[c];
			U[cnt] = c;
			D[c] = cnt;
			L[cnt] = tail;
			R[tail] = cnt;
			R[cnt] = head;
			L[head] = cnt;
			tail = cnt;
			cnt ++;
		}
	}
	int best = 0, worst = maxdepth;
	/*while (best <= worst) {
		limit = (worst + best) >> 1;
		if (dfs(0)) worst = limit - 1;
		else best = limit + 1;
	}*/
	limit = maxdepth;
	if(dfs(0))best = maxdepth;
	else
		best = maxdepth+1;
	return best;
}

int x[155],y[155];

int dij(int i, int j)
{
	int d1 = (x[i]-x[j])*(x[i]-x[j]);
	int d2 = (y[i]-y[j])*(y[i]-y[j]);
	return d1+d2;
}

int main()
{
	int i,j,k,l,row,col,n,m,low,up,mid,mark[MAXN][MAXN],d[55][55],T,b[3000],top;


	scanf("%d",&T);
	while(T--)
	{
		scanf("%d %d %d",&n,&row,&m);

		for(i=1;i<=n+row;i++)
			scanf("%d %d",&x[i],&y[i]);
	
		low = 1; up = 1000000000;

		while(low < up)
		{
			for(i=1;i<=row;i++)
				for(j=1;j<=n;j++)mark[i][j] = 0;
		
			mid = (low + up)>>1;
			for(i=1;i<=row;i++)
				for(j=1;j<=n;j++)if(dij(i+n,j) <= mid)mark[i][j] = 1;
			
			if(solve(row, n, mark, m) > m)low = mid+1; else up = mid;
		}
		mid = (low + up)>>1;
		printf("%.6lf\n",sqrt(1.0*mid));
	}
	return 0;
}