[20250817] BOJ / G3 / 내리막 길/ 이종환

Author: 0224LJH

0224LJH/202508/17 BOJ 내리막 길.md

@@ -0,0 +1,75 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static int height,width;
+    static int[][] arr;
+    static int[][] dp;
+    static int[] dy = {-1,0,1,0};
+    static int[] dx = {0,1,0,-1};
+
+
+    public static void main(String[] args) throws Exception {
+        init();
+        process();
+        print();
+
+    }
+
+    public static void init() throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        height = Integer.parseInt(st.nextToken());
+        width = Integer.parseInt(st.nextToken());
+        arr = new int[height][width];
+        dp = new int[height][width];
+
+        for (int i = 0; i < height; i++) {
+            Arrays.fill(dp[i],-1);
+            st = new StringTokenizer(br.readLine());
+            for (int j = 0; j < width; j++) {
+                arr[i][j] = Integer.parseInt(st.nextToken());
+            }
+        }
+
+
+    }
+
+    public static void process(){
+        dfs(0,0);
+    }
+
+    public static void print(){
+
+        System.out.println(dp[0][0]);
+    }
+
+    public static int dfs(int y, int x){
+        if ( y == height - 1 && x == width - 1 ) {
+            return 1;
+        }
+
+
+        if(dp[y][x] != -1) return dp[y][x];
+
+        dp[y][x] = 0;
+
+        for (int i = 0; i < 4; i++){
+            int ny = y + dy[i];
+            int nx = x + dx[i];
+            if (ny < 0 || ny >= height || nx < 0 || nx >= width) continue;
+            if (arr[ny][nx] >= arr[y][x]) continue;
+
+            dp[y][x] += dfs(ny, nx);
+        }
+
+        return dp[y][x];
+
+    }
+
+}
+
+
+```