fix a bug in bfs01; add multisouce feature; Refactor GridGraph to use…

graph/grid_graph_template.hpp

@@ -5,32 +5,34 @@
 #include <tuple>
 #include <utility>
 #include <vector>
+#include <functional>
 
 // CUT begin
-template <typename T_E, T_E INF, T_E (*edge_cost)(int, int, int, int)> struct GridGraph {
+template <typename T_E, T_E INF> struct GridGraph {
     const int H, W;
     const std::vector<int> dx{1, -1, 0, 0};
     const std::vector<int> dy{0, 0, 1, -1};
+    // T_E (*edge_cost)(int, int, int, int);
+    std::function<T_E(int, int, int, int)> edge_cost;
 
     GridGraph() = default;
-    GridGraph(int h, int w) : H(h), W(w) {}
+    GridGraph(int h, int w, std::function<T_E(int, int, int, int)> _edge_cost)
+        : H(h), W(w), edge_cost(move(_edge_cost)) {}
 
     // Dijkstra's algorithm
     // Complexity: O(HWlog(HW))
     std::vector<std::vector<T_E>> dist;                // Distance from (x_s, y_s)
     std::vector<std::vector<std::pair<int, int>>> prv; // Previous node for Dijkstra optimal path
-    void dijkstra(int x_s, int y_s) {
+    void dijkstra(int x_s, int y_s) { dijkstra({x_s, y_s}); }
+    void dijkstra(std::vector<std::pair<int, int>> xy_s) {
         dist.assign(H, std::vector<T_E>(W, INF));
         prv.assign(H, std::vector<std::pair<int, int>>(W, std::make_pair(-1, -1)));
 
         using P = std::tuple<T_E, int, int>;
         std::priority_queue<P, std::vector<P>, std::greater<P>> pq;
-        dist[x_s][y_s] = 0;
-        pq.emplace(0, x_s, y_s);
+        for (auto [x_s, y_s] : xy_s) dist[x_s][y_s] = 0, pq.emplace(0, x_s, y_s);
         while (!pq.empty()) {
-            T_E dnow;
-            int x, y;
-            std::tie(dnow, x, y) = pq.top();
+            auto [dnow, x, y] = pq.top();
             pq.pop();
             if (dist[x][y] < dnow) continue;
             for (unsigned d = 0; d < dx.size(); d++) {
@@ -46,28 +48,29 @@ template <typename T_E, T_E INF, T_E (*edge_cost)(int, int, int, int)> struct Gr
         }
     }
 
-    void bfs_01(int x_s, int y_s) {
+    void bfs_01(int x_s, int y_s) { bfs_01({x_s, y_s}); }
+    void bfs_01(std::vector<std::pair<int, int>> xy_s) {
+        std::deque<std::pair<int, int>> deq;
         dist.assign(H, std::vector<T_E>(W, INF));
         prv.assign(H, std::vector<std::pair<int, int>>(W, std::make_pair(-1, -1)));
-        std::deque<std::pair<int, int>> deq;
-        dist[x_s][y_s] = 0;
-        deq.emplace_back(x_s, y_s);
+        for (auto [x_s, y_s] : xy_s) dist[x_s][y_s] = 0, deq.emplace_back(x_s, y_s);
         while (!deq.empty()) {
-            int x, y;
-            std::tie(x, y) = deq.front();
-            const auto dnow = dist[x][y];
+            auto [x, y] = deq.front();
             deq.pop_front();
+            const auto dnow = dist[x][y];
             for (unsigned d = 0; d < dx.size(); d++) {
                 int xn = x + dx[d], yn = y + dy[d];
                 if (xn < 0 or yn < 0 or xn >= H or yn >= W) continue;
-                auto dnxt = dnow + edge_cost(x, y, xn, yn);
+                auto cost = edge_cost(x, y, xn, yn);
+                auto dnxt = dnow + cost;
                 if (dnxt < dist[xn][yn]) {
                     dist[xn][yn] = dnxt;
                     prv[xn][yn] = std::make_pair(x, y);
-                    if (dnxt)
+                    if (cost > 0) {
                         deq.emplace_back(xn, yn);
-                    else
+                    } else {
                         deq.emplace_front(xn, yn);
+                    }
                 }
             }
         }