delete pics to save space

2.658.cpp

@@ -0,0 +1,72 @@
+// UVa658 It's not a Bug, it's a Feature!
+// Rujia Liu
+#include<cstdio>
+#include<cstring>
+#include<queue>
+using namespace std;
+
+struct Node {
+  int bugs, dist;
+  bool operator < (const Node& rhs) const {
+    return dist > rhs.dist;
+  }
+};
+
+const int maxn = 20;
+const int maxm = 100 + 5;
+const int INF = 1000000000;
+
+int n, m, t[maxm], dist[1<<maxn], mark[1<<maxn];
+char before[maxm][maxn + 5], after[maxm][maxn + 5];
+
+int solve() {
+  for(int i = 0; i < (1<<n); i++) { mark[i] = 0; dist[i] = INF; }
+  priority_queue<Node> q;
+
+  Node start;
+  start.dist = 0;
+  start.bugs = (1<<n) - 1;
+  q.push(start);
+
+  dist[start.bugs] = 0;
+  while(!q.empty()) {
+    Node u = q.top(); q.pop();
+    if(u.bugs == 0) return u.dist;
+    if(mark[u.bugs]) continue;
+    mark[u.bugs] = 1;
+    for(int i = 0; i < m; i++) {
+      bool patchable = true;
+      for(int j = 0; j < n; j++) {
+        if(before[i][j] == '-' && (u.bugs & (1<<j))) { patchable = false; break; }
+        if(before[i][j] == '+' && !(u.bugs & (1<<j))) { patchable = false; break; }
+      }
+      if(!patchable) continue;
+
+      Node u2;
+      u2.dist = u.dist + t[i];
+      u2.bugs = u.bugs;
+      for(int j = 0; j < n; j++) {
+        if(after[i][j] == '-') u2.bugs &= ~(1<<j);
+        if(after[i][j] == '+') u2.bugs |= (1<<j);
+      }
+      int& D = dist[u2.bugs];
+      if(D < 0 || u2.dist < D) {
+        D = u2.dist;
+        q.push(u2);
+      }
+    }
+  }
+  return -1;
+}
+
+int main() {
+  int kase = 0;
+  while(scanf("%d%d", &n, &m) == 2 && n) {
+    for(int i = 0; i < m; i++) scanf("%d%s%s", &t[i], before[i], after[i]);
+    int ans = solve();
+    printf("Product %d\n", ++kase);
+    if(ans < 0) printf("Bugs cannot be fixed.\n\n");
+    else printf("Fastest sequence takes %d seconds.\n\n", ans);
+  }
+  return 0;
+}