首页 > 代码库 > UVA - 10305 Ordering Tasks(拓扑排序)
UVA - 10305 Ordering Tasks(拓扑排序)
题意:给定优先关系进行拓扑排序。
分析:将入度为0的点加入优先队列,并将与之相连的点入度减1,若又有度数为0的点,继续加入优先队列,依次类推。
#pragma comment(linker, "/STACK:102400000, 102400000") #include<cstdio> #include<cstring> #include<cstdlib> #include<cctype> #include<cmath> #include<iostream> #include<sstream> #include<iterator> #include<algorithm> #include<string> #include<vector> #include<set> #include<map> #include<stack> #include<deque> #include<queue> #include<list> #define Min(a, b) ((a < b) ? a : b) #define Max(a, b) ((a < b) ? b : a) typedef long long ll; typedef unsigned long long llu; const int INT_INF = 0x3f3f3f3f; const int INT_M_INF = 0x7f7f7f7f; const ll LL_INF = 0x3f3f3f3f3f3f3f3f; const ll LL_M_INF = 0x7f7f7f7f7f7f7f7f; const int dr[] = {0, 0, -1, 1, -1, -1, 1, 1}; const int dc[] = {-1, 1, 0, 0, -1, 1, -1, 1}; const int MOD = 1e9 + 7; const double pi = acos(-1.0); const double eps = 1e-8; const int MAXN = 100 + 10; const int MAXT = 10000 + 10; using namespace std; int in[MAXN]; vector<int> a[MAXN]; vector<int> ans; priority_queue<int, vector<int>, greater<int> > q; int main(){ int n, m; while(scanf("%d%d", &n, &m) == 2){ if(!n && !m) return 0; memset(in, 0, sizeof in); ans.clear(); for(int i = 0; i < MAXN; ++i) a[i].clear(); while(m--){ int x, y; scanf("%d%d", &x, &y); a[x].push_back(y); ++in[y]; } for(int i = 1; i <= n; ++i){ if(in[i] == 0){ q.push(i); } } while(!q.empty()){ int t = q.top(); q.pop(); ans.push_back(t); int len = a[t].size(); for(int i = 0; i < len; ++i){ if(--in[a[t][i]] == 0){ q.push(a[t][i]); } } } int len = ans.size(); for(int i = 0; i < len; ++i){ if(i) printf(" "); printf("%d", ans[i]); } printf("\n"); } return 0; }
UVA - 10305 Ordering Tasks(拓扑排序)
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