[20251030] PGM / LV3 / 등굣길 / 강신지

Author: ksinji

ksinji/202510/30 PGM 등굣길.md

@@ -0,0 +1,34 @@
+```java
+class Solution {
+    static final int MOD = 1000000007;
+    public int solution(int m, int n, int[][] puddles) {
+        int[][] dp = new int[n+1][m+1];
+        
+        dp[1][1] = 1;
+        
+        for (int[] p: puddles){
+            dp[p[1]][p[0]] = -1;
+        }
+        
+        for (int i=1; i<n+1; i++){
+            for (int j=1; j<m+1; j++){
+                if (i==1 && j==1){
+                    continue;
+                }
+                
+                if (dp[i][j] == -1) {
+                    continue;
+                } else if (dp[i-1][j] == -1) {
+                    dp[i][j] = dp[i][j-1]%MOD;
+                } else if (dp[i][j-1] == -1) {
+                    dp[i][j] = dp[i-1][j]%MOD;
+                } else {
+                    dp[i][j] = (dp[i][j-1]+dp[i-1][j])%MOD;
+                }
+            }
+        }
+        
+        return dp[n][m];
+    }
+}
+```