Update CMakeLists.txt

dp/SHOI2002_ski_dp.cpp

@@ -0,0 +1,110 @@
+#include <algorithm>
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+struct Node {
+    int x, y, height;
+};
+
+constexpr int MAX_N = 105;
+constexpr short DX[4] = {0, 1, 0, -1}, DY[4] = {1, 0, -1, 0};
+int r, c;
+int heights[MAX_N][MAX_N];
+vector<int> adj_nodes[MAX_N * MAX_N];
+vector<Node> nodes;
+
+int dp[MAX_N * MAX_N];
+
+int pack_coord(int x, int y) {
+    return x * c + y;
+}
+
+int pack_coord(Node node) {
+    return pack_coord(node.x, node.y);
+}
+
+bool within_board(int x, int y) {
+    return 0 <= x && x < r && 0 <= y && y < c;
+}
+
+
+void log_dp() {
+    for (int i = 0; i < r * c; i++) {
+        clog << dp[i] << "\t";
+        if (i % c == c - 1) {
+            clog << endl;
+        }
+    }
+}
+
+void log_adj_nodes() {
+    for (int i = 0; i < r * c; i++) {
+        clog << i << " -> ";
+        for (int adj_node : adj_nodes[i]) {
+            clog << adj_node << " ";
+        }
+        clog << endl;
+    }
+}
+
+void init_adj_nodes() {
+    for (int i = 0; i < r; i++) {
+        for (int j = 0; j < c; j++) {
+            nodes.push_back({i, j, heights[i][j]});
+            int x = i, y = j;
+            for (int k = 0; k < 4; k++) {
+                int nx = x + DX[k], ny = y + DY[k];
+                if (within_board(nx, ny) && heights[nx][ny] > heights[x][y]) {
+                    // 反向建图，小 -> 大
+                    adj_nodes[pack_coord(x, y)].push_back(pack_coord(nx, ny));
+                }
+            }
+        }
+    }
+    sort(nodes.begin(), nodes.end(), [](const Node& a, const Node& b) {
+        return a.height > b.height;
+    });
+}
+
+
+void solve_dp() {
+    dp[pack_coord(nodes[0])] = 1;
+    for (int i = 1; i < nodes.size(); i++) {
+        Node curr_node = nodes[i];
+        int max_dp = 0;
+        for (int adj_node : adj_nodes[pack_coord(curr_node)]) {
+            max_dp = max(max_dp, dp[adj_node]);
+        }
+        dp[pack_coord(curr_node)] = max_dp + 1;
+    }
+}
+
+int get_ans() {
+    int max_dp = -1;
+    for (int i = 0; i < r * c; i++) {
+        max_dp = max(max_dp, dp[i]);
+    }
+    return max_dp;
+}
+
+int main() {
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> r >> c;
+    for (int i = 0; i < r; i++) {
+        for (int j = 0; j < c; j++) {
+            cin >> heights[i][j];
+        }
+    }
+
+    init_adj_nodes();
+    solve_dp();
+    log_adj_nodes();
+    log_dp();
+    cout << get_ans() << endl;
+
+    return 0;
+}