add: Pacific Atlantic Water Flow

Author: Yongseok-Choi-dev

clone-graph/Solution.java renamed to clone-graph/YoungSeok-Choi.java

@@ -83,4 +83,4 @@ public void print(Node node) {
             print(adj);
         }
     }
-}
+}

linked-list-cycle/Solution.java renamed to linked-list-cycle/YoungSeok-Choi.java

@@ -64,4 +64,4 @@ public boolean hasCycle(ListNode head) {
             return false;
         }
     }
-}
+}

pacific-atlantic-water-flow/YoungSeok-Choi.java

@@ -0,0 +1,113 @@
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+// TC -> O(nm^2) 일 것으로 예상.. 
+class Solution {
+
+    public boolean[][] visit;
+    public List<List<Integer>> res = new ArrayList<>();
+    public int w;
+    public int h;
+
+    public int[] dx = { 0, 1, 0, -1 };
+    public int[] dy = { 1, 0, -1, 0 };
+
+    public List<List<Integer>> pacificAtlantic(int[][] heights) {
+        w = heights.length;
+        h = heights[0].length;
+
+        if (w == h && w == 1) {
+            res.add(Arrays.asList(0, 0));
+            return res;
+        }
+
+        for (int i = 0; i < w; i++) {
+            for (int j = 0; j < h; j++) {
+
+                boolean isTrue = false;
+                visit = new boolean[w][h];
+
+                isTrue |= dfsP(i, j, heights[i][j], heights);
+
+                visit = new boolean[w][h];
+
+                isTrue &= dfsA(i, j, heights[i][j], heights);
+
+                if (isTrue) {
+                    res.add(Arrays.asList(i, j));
+                }
+            }
+        }
+
+        return res;
+    }
+
+    public boolean dfsP(int x, int y, int prev, int[][] map) {
+        if (x < 0 || y < 0) {
+            return true;
+        }
+
+        if (x >= w || y >= h) {
+            return false;
+        }
+
+        if (visit[x][y]) {
+            return false;
+        }
+
+        if (prev < map[x][y]) {
+            return false;
+        }
+
+        visit[x][y] = true;
+
+        boolean isTrue = false;
+        for (int i = 0; i < 4; i++) {
+            int nx = x + dx[i];
+            int ny = y + dy[i];
+
+            isTrue |= dfsP(nx, ny, map[x][y], map);
+            if (isTrue) {
+                return true;
+            }
+        }
+
+        return isTrue;
+    }
+
+    public boolean dfsA(int x, int y, int prev, int[][] map) {
+        if (x < 0 || y < 0) {
+            return false;
+        }
+
+        if (x >= w || y >= h) {
+            return true;
+        }
+
+        if (visit[x][y]) {
+            return false;
+        }
+
+        if (prev < map[x][y]) {
+            return false;
+        }
+
+        visit[x][y] = true;
+
+        boolean isTrue = false;
+        for (int i = 0; i < 4; i++) {
+            int nx = x + dx[i];
+            int ny = y + dy[i];
+
+            isTrue |= dfsA(nx, ny, map[x][y], map);
+
+            if (isTrue) {
+                return true;
+            }
+
+        }
+
+        return isTrue;
+    }
+}