feat : leetCode DP uniquePaths

Author: cyeji

src/main/java/sgyj/leetcode/Readme.md

@@ -33,3 +33,4 @@
 - [746. Min Cost Climbing Stairs](https://leetcode.com/problems/min-cost-climbing-stairs/description/)
 - [128. Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence/)
 - [322. Coin Change](https://leetcode.com/problems/coin-change/description/)
+- [62. Unique Paths](https://leetcode.com/problems/unique-paths/description/)

src/main/java/sgyj/leetcode/yeji/section6/Solution62.java

@@ -0,0 +1,43 @@
+package sgyj.leetcode.yeji.section6;
+
+// 62. Unique Paths
+/*
+There is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]).
+The robot tries to move to the bottom-right corner (i.e., grid[m - 1][n - 1]). The robot can only move either down or right at any point in time.
+Given the two integers m and n, return the number of possible unique paths that the robot can take to reach the bottom-right corner.
+The test cases are generated so that the answer will be less than or equal to 2 * 109.
+*/
+
+public class Solution62 {
+    private static int[][] visited;
+    private static int answer = 0;
+    public static int uniquePaths(int m, int n) {
+
+        visited = new int[m][n];
+        visited[0][0] = 1;
+
+        for(int i=0; i<m; i++){
+            for(int j=0; j<n; j++){
+                int dx = 0;
+                int dy = 0;
+                if(i-1>=0){
+                    dx = visited[i-1][j];
+                }
+                if(j-1>=0){
+                    dy = visited[i][j-1];
+                }
+                visited[i][j] = dx+dy == 0 ? 1 : dx+dy;
+            }
+        }
+
+        return visited[m-1][n-1];
+    }
+
+    public static void main ( String[] args ) {
+        int m = 3;
+        int n = 2;
+
+        System.out.println(uniquePaths(m,n));
+
+    }
+}