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