solve unique paths

Author: sora0319

unique-paths/sora0319.java

@@ -0,0 +1,44 @@
+class Solution {
+    public int uniquePaths(int m, int n) {
+        int[][] pathN = new int[m][n];
+        boolean[][] visited = new boolean[m][n];
+        pathN[0][0] = 1;
+
+        bfs(pathN, visited);
+        return pathN[m-1][n-1];
+    }
+    public void bfs(int[][] pathN, boolean[][] visited){
+        Queue<Pair> paths = new LinkedList<>();
+        int[] mx = {0, 1};
+        int[] my = {1, 0};
+
+        paths.offer(new Pair(0,0));
+
+        while(!paths.isEmpty()){
+            Pair p = paths.poll();
+
+            for(int i = 0; i < 2; i++){
+                int nx = mx[i] + p.x;
+                int ny = my[i] + p.y;
+
+                if(nx >= pathN.length || ny >= pathN[0].length) continue;
+                pathN[nx][ny] += pathN[p.x][p.y];
+                if(!visited[nx][ny]){
+                    paths.offer(new Pair(nx, ny));
+                    visited[nx][ny] = true;
+                }
+
+            }
+        }
+    }
+
+    class Pair{
+        int x;
+        int y;
+        Pair(int x, int y){
+            this.x = x;
+            this.y = y;
+        }
+    }
+}
+