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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,41 @@ | ||
| /* Eulerian Circuit (directed) */ | ||
| // Hierholzer’s Algorithm | ||
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| /* | ||
| CPH: | ||
| https://cses.fi/book/book.pdf#page=183 | ||
| Hello world: | ||
| https://cses.fi/problemset/task/1693 | ||
| */ | ||
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| vector<int> indeg(n), outdeg(n); | ||
| vector<vector<int>> g(n); | ||
| for(i = 0; i < m; i++) { | ||
| int u, v; cin >> u >> v; | ||
| outdeg[--u]++; indeg[--v]++; | ||
| g[u].push_back(v); | ||
| } | ||
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| bool bad = false; | ||
| for(i = 1; i < n-1; i++) | ||
| bad |= outdeg[i] ^ indeg[i]; | ||
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| bad |= outdeg[0]-indeg[0] ^ 1; | ||
| bad |= indeg[n-1]-outdeg[n-1] ^ 1; | ||
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| if(bad) | ||
| // IMPOSSIBLE | ||
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| vector<int> tour; | ||
| tour.reserve(m+1); | ||
| Y([&](auto dfs, int v) -> void { | ||
| while(outdeg[v]-- > 0) | ||
| dfs(g[v][outdeg[v]]); | ||
| tour.push_back(v); | ||
| })(0); | ||
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| for(i = 0; i < n; i++) | ||
| if(outdeg[i] > 0) | ||
| // IMPOSSIBLE | ||
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| reverse(tour.begin(), tour.end()); |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,51 @@ | ||
| /* Eulerian Circuit (undirected) */ | ||
| // Hierholzer’s Algorithm | ||
|
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| /* | ||
| CPH: | ||
| https://cses.fi/book/book.pdf#page=183 | ||
| Hello world: | ||
| https://cses.fi/problemset/task/1691 | ||
| */ | ||
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| struct edge_t { | ||
| int u{-1}, v{-1}; bool done{false}; | ||
| edge_t() = default; | ||
| edge_t(int u, int v) : u(u), v(v) {} | ||
| }; | ||
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| vector<int> deg(n); | ||
| vector<edge_t> edges; | ||
| edges.reserve(m); | ||
| vector<vector<edge_t*>> g(n); | ||
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| for(i = 0; i < m; i++) { | ||
| int u, v; cin >> u >> v; | ||
| deg[--u]++; deg[--v]++; | ||
| edges.emplace_back(u, v); | ||
| g[u].push_back(&edges.back()); | ||
| g[v].push_back(&edges.back()); | ||
| } | ||
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| bool bad = false; | ||
| for(i = 0; i < n; i++) | ||
| bad |= deg[i] & 1; | ||
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| if(bad) | ||
| // IMPOSSIBLE | ||
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| vector<int> tour; | ||
| tour.reserve(m+1); | ||
| Y([&](auto dfs, int v) -> void { | ||
| while(deg[v]-- > 0) { | ||
| auto e = g[v][deg[v]]; | ||
| if(!e->done) | ||
| e->done = true, dfs(e->u ^ e->v ^ v); | ||
| } tour.push_back(v); | ||
| })(0); | ||
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| for(i = 0; i < n; i++) | ||
| if(deg[i] > 0) | ||
| // IMPOSSIBLE | ||
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| reverse(tour.begin(), tour.end()); |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,43 +1,24 @@ | ||
| /* Floyd-Warshall's all pair shortest paths */ | ||
| // (https://cp-algorithms.com/graph/all-pair-shortest-path-floyd-warshall.html) | ||
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| int d[N][N]; | ||
| vector<int> ans; | ||
| /* | ||
| https://github.com/the-hyp0cr1t3/CC/blob/master/Beginner%20Topics/%5BS5%5D%20Do%20you%20understand%20the%20graphity%20of%20this%20situation/%5BEP%202%5D%20Shortest%20paths/%5BPt%203%5D%20Floyd-Warshall.md | ||
| */ | ||
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| for(i = 0; i < n; i++) { | ||
| for(j = 0; j < n; j++) { | ||
| d[i][j] = INF; | ||
| p[i][j] = -1; | ||
| } | ||
| d[i][i] = 0; | ||
| p[i][i] = 0; | ||
| } | ||
| auto chmin = [](auto& A, auto&& B) { return B < A? A = B, true : false; }; | ||
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| for(i = 0; i < m; i++) { | ||
| int u, v, cost; | ||
| cin >> u >> v >> cost; | ||
| u--, v--; | ||
| d[u][v] = d[v][u] = cost; | ||
| p[u][v] = v; | ||
| p[v][u] = u; | ||
| } | ||
| vector d(n, vector<int>(n, INF)), path(n, vector<int>(n, -1)); | ||
| for(auto [u, v, w]: edges) | ||
| d[u][v] = w, path[u][v] = v; | ||
| // d[i][i] = 0; | ||
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| void warshall() { | ||
| for(int k = 0; k < n; k++) { | ||
| for(int i = 0; i < n; i++) { | ||
| for(int j = 0; j < n; j++) { | ||
| if(d[i][k]^INF and d[k][j]^INF and (d[i][k]+d[k][j] < d[i][j])) { | ||
| d[i][j] = d[i][k] + d[k][j]; | ||
| p[i][j] = p[i][k]; | ||
| } | ||
| } | ||
| } | ||
| } | ||
| }; | ||
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| void path(int u, int v) { | ||
| ans.pb(u+1); | ||
| if(u == v) return; | ||
| path(p[u][v], v); | ||
| } | ||
| for(int k = 0; k < n; k++) | ||
| for(int i = 0; i < n; i++) | ||
| for(int j = 0; j < n; j++) | ||
| if(chmin(d[i][j], d[i][k] + d[k][j])) | ||
| path[i][j] = path[i][k]; | ||
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| vector<int> ans{ u }; | ||
| while(u ^ v) { | ||
| u = path[u][v]; | ||
| ans.push_back(u); | ||
| } |
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