commit 347510bb35a95aae7764aec63c367012eceebb85
Author: Antoine Amarilli <a3nm@a3nm.net>
Date: Sun, 8 Mar 2015 13:34:45 +0100
initial commit
Diffstat:
12 files changed, 302 insertions(+), 0 deletions(-)
diff --git a/decontamination.cpp b/decontamination.cpp
@@ -0,0 +1,130 @@
+/* decontamination.cpp -- find decontamination sequence of input graph
+ * Antoine Amarilli, 2015
+ * see http://cstheory.stackexchange.com/q/30592/4795 for problem statement
+ *
+ * To use, set MAXN in the code to be more than the number of vertices to
+ * consider, and compile with g++ -Wall -O3 -std=c++11
+ *
+ * Provide graph in stdin with each edge represented by the source and target
+ * represented as integers, separated by a space, edges separated by newline.
+ * EOF terminates. Vertices should be numbered from 0 to n-1.
+ *
+ * Output is a decontamination sequence with minimal number of nodes to be
+ * simultaneously decontaminated, then minimal order, then (normally) minimum in
+ * lexicographic order, represented as a bit vector of the node contaminations
+ * separated by the nodes to query. */
+
+// max number of vertices, change this
+#define MAXN 32
+
+#include <cstdio>
+#include <iostream>
+#include <assert.h>
+#include <queue>
+#include <bitset>
+#include <algorithm>
+#include <unordered_map>
+
+#define max(a, b) ((b)>(a) ? (b) : (a))
+
+using namespace std;
+
+int main() {
+ // n_vertices, n_edges
+ int n = 0;
+ // adjacency lists
+ int G[MAXN][MAXN];
+ // degrees
+ int nG[MAXN];
+
+ for (int i = 0; i < MAXN; i++)
+ nG[i] = 0;
+ while (true) {
+ int f, t, ret;
+ ret = scanf("%d %d\n", &f, &t);
+ if (ret != 2)
+ break;
+ // vertices should be numbered from 0 to n-1 with n <= MAXN
+ assert(0 <= f && f < MAXN && 0 <= t && t < MAXN);
+ n = max(n, max(f, t));
+ G[f][nG[f]] = t;
+ nG[f]++;
+ }
+ n++; // so that vertices are from 0 to n-1
+
+ for (int k = 1; k <= n; k++) {
+ // decontaminate simultaneously k nodes
+ // do a BFS on configurations
+
+ // queue of configurations to consider
+ queue<bitset<MAXN> > q;
+ // predecessor configuration of each reachable configuration
+ unordered_map<bitset<MAXN>, bitset<MAXN> > p;
+ // action to reach each reachable configuration from predecessor
+ unordered_map<bitset<MAXN>, string > a;
+
+ // start configuration
+ bitset<MAXN> s;
+ for (int i = 0; i < n; i++)
+ s.set(i);
+ q.push(s);
+
+ while (!q.empty()) {
+ bitset<MAXN> c = q.front();
+ if (!c.count())
+ break; // target configuration reached
+ q.pop();
+ // http://rosettacode.org/wiki/Combinations#C.2B.2B
+ string bm(k, 1);
+ bm.resize(n, 0);
+ do {
+ bitset<MAXN> nc; // new possible configuration
+ for (int i = 0; i < n; i++)
+ if (c[i] && !bm[i])
+ // i is contaminated and was not decontaminated at this turn
+ for (int j = 0; j < nG[i]; j++)
+ // all possible contaminations by i
+ nc.set(G[i][j]);
+ if (!p.count(nc)) {
+ // nc was not reachable yet
+ p[nc] = c;
+ a[nc] = bm;
+ q.push(nc);
+ }
+ } while (prev_permutation(bm.begin(), bm.end()));
+ }
+
+ bitset<MAXN> e;
+ if (p.count(e)) {
+ // target configuration was reached: all nodes decontaminated
+ // read back the path to the target configuration
+ vector<string> v;
+ do {
+ v.push_back(e.to_string());
+ v.push_back(a[e]);
+ e = p[e];
+ } while (p.count(e) && p[e] != e);
+ v.push_back(e.to_string());
+ // path is in reverse order
+ reverse(v.begin(), v.end());
+ for (unsigned int i = 0; i < v.size(); i++) {
+ if (i % 2 == 1) {
+ // display decontamination action
+ for (int j = 0; j < n; j++) {
+ if (v[i][j])
+ printf("%d ", j);
+ }
+ } else {
+ // display configuration
+ cout << v[i];
+ }
+ printf("\n");
+ }
+ break;
+ }
+ // if target configuration was not reached, increase k
+ }
+
+ return 0;
+}
+
diff --git a/graphs/big b/graphs/big
@@ -0,0 +1,18 @@
+0 1
+1 0
+1 2
+2 1
+2 3
+3 2
+0 4
+4 0
+4 5
+5 4
+5 6
+6 5
+0 7
+7 0
+8 7
+7 8
+8 9
+9 8
diff --git a/graphs/bigcycle2 b/graphs/bigcycle2
@@ -0,0 +1,14 @@
+0 1
+1 0
+1 2
+2 1
+2 3
+3 2
+3 4
+4 3
+4 5
+5 4
+5 6
+6 5
+6 0
+0 6
diff --git a/graphs/cycle b/graphs/cycle
@@ -0,0 +1,4 @@
+0 1
+1 2
+2 3
+3 0
diff --git a/graphs/cycle2 b/graphs/cycle2
@@ -0,0 +1,8 @@
+0 1
+1 0
+1 2
+2 1
+2 3
+3 2
+3 0
+0 3
diff --git a/graphs/line b/graphs/line
@@ -0,0 +1,8 @@
+0 1
+1 0
+1 2
+2 1
+2 3
+3 2
+3 4
+4 3
diff --git a/graphs/linei b/graphs/linei
@@ -0,0 +1,42 @@
+0 1
+1 0
+1 2
+2 1
+2 3
+3 2
+3 4
+4 3
+4 5
+5 4
+5 6
+6 5
+6 7
+7 6
+1 8
+8 1
+1 9
+9 1
+8 10
+10 8
+8 11
+11 8
+3 12
+12 3
+12 13
+13 12
+3 14
+14 3
+14 15
+15 14
+6 16
+16 6
+16 17
+17 16
+6 18
+18 6
+18 19
+19 18
+18 20
+20 18
+20 21
+21 20
diff --git a/graphs/star b/graphs/star
@@ -0,0 +1,12 @@
+0 1
+1 0
+1 2
+2 1
+0 3
+3 0
+3 4
+4 3
+0 5
+5 0
+6 5
+5 6
diff --git a/graphs/star2 b/graphs/star2
@@ -0,0 +1,14 @@
+0 1
+1 0
+1 2
+2 1
+0 3
+3 0
+3 4
+4 3
+0 5
+5 0
+6 5
+5 6
+6 7
+7 6
diff --git a/graphs/star3 b/graphs/star3
@@ -0,0 +1,16 @@
+0 1
+1 0
+1 2
+2 1
+0 3
+3 0
+3 4
+4 3
+0 5
+5 0
+6 5
+5 6
+0 6
+6 0
+6 7
+7 6
diff --git a/graphs/star3b b/graphs/star3b
@@ -0,0 +1,18 @@
+0 1
+1 0
+1 2
+2 1
+0 3
+3 0
+3 4
+4 3
+0 5
+5 0
+6 5
+5 6
+0 7
+7 0
+8 7
+7 8
+8 9
+9 8
diff --git a/graphs/starau b/graphs/starau
@@ -0,0 +1,18 @@
+0 1
+1 0
+1 2
+2 1
+0 3
+3 0
+3 4
+4 3
+0 5
+5 0
+6 5
+5 6
+1 7
+7 1
+7 8
+8 7
+8 9
+9 8
