62. Unique Paths

Author: zj

code/062. Unique Paths/README.md

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+# 62. Unique Paths
+A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).
+
+The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in the diagram below).
+
+How many possible unique paths are there?
+
+[img](http://leetcode.com/wp-content/uploads/2014/12/robot_maze.png)
+
+Above is a 3 x 7 grid. How many possible unique paths are there?
+
+Note: m and n will be at most 100.

code/062. Unique Paths/index.js

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+/**
+ * @param {number} m
+ * @param {number} n
+ * @return {number}
+ */
+//Distribution 89.58%,runtime 96ms
+var uniquePaths = function(m, n) {
+    var list = [];
+    for(var x = 0; x < m; x++)
+        list[x] = [];
+    list[0][0] = 1;
+    for(x = 0; x < m; x++){
+        for(var y = 0; y < n; y++){
+            if(x === 0 || y === 0) list[x][y] = 1;
+            else list[x][y] = list[x - 1][y] + list[x][y - 1];
+        }
+    }
+    return list[m - 1][n - 1];
+};