Add Leet Code Solution of 62 No Ques (#1061)

Co-authored-by: Utsav Khemka <utsav9125368000@gmail.com>

leetcode/README.md

@@ -1,11 +1,9 @@
-LeetCode
-========
+# LeetCode
 
 ### LeetCode Algorithm
 
-
 | #    | Title                                                                                                                           | Solution          | Difficulty |
-|---| ----- | -------- | ---------- |
+| ---- | ------------------------------------------------------------------------------------------------------------------------------- | ----------------- | ---------- |
 | 1    | [Two Sum](https://leetcode.com/problems/two-sum/)                                                                               | [C](./src/1.c)    | Easy       |
 | 2    | [Add Two Numbers](https://leetcode.com/problems/add-two-numbers/)                                                               | [C](./src/2.c)    | Medium     |
 | 3    | [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/) | [C](./src/3.c)    | Medium     |
@@ -27,6 +25,7 @@ LeetCode
 | 35   | [Search Insert Position](https://leetcode.com/problems/search-insert-position/)                                                 | [C](./src/35.c)   | Easy       |
 | 38   | [Count and Say](https://leetcode.com/problems/count-and-say/)                                                                   | [C](./src/38.c)   | Easy       |
 | 53   | [Maximum Subarray](https://leetcode.com/problems/maximum-subarray/)                                                             | [C](./src/53.c)   | Easy       |
+| 62   | [Unique Paths](https://leetcode.com/problems/unique-paths/description/)                                                         | Medium            |
 | 66   | [Plus One](https://leetcode.com/problems/plus-one/)                                                                             | [C](./src/66.c)   | Easy       |
 | 82   | [Remove Duplicates from Sorted List II](https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/)                   | [C](./src/82.c)   | Medium     |
 | 83   | [Remove Duplicates from Sorted List](https://leetcode.com/problems/remove-duplicates-from-sorted-list/)                         | [C](./src/83.c)   | Easy       |

leetcode/src/62.c

@@ -0,0 +1,39 @@
+// Dynamic programming can be applied here, because every solved sub-problem has
+// an optimal sub-solution
+// Searching backwards from end to start, we can incrementally calculate number
+// of paths to destination. i.e. start from bottom-right, and calculate
+// leftwards (lowest row should all be 1). then go to second-last-row, rightmost
+// column, and calculate leftwards the last cell to be calculated is the start
+// location (0, 0). The iteration ordering is intentional: the inner loop
+// iterates the contents of each vector, the outer loop iterates each vector.
+// This is more cache-friendly.
+
+// Example below, calculated from right-to-left, bottom-to-top.
+// 7 by 3 grid
+// 28 21 15 10  6  3  1
+//  7  6  5  4  3  2  1
+//  1  1  1  1  1  1  1
+
+int uniquePaths(int m, int n)
+{
+    int dp[m][n];
+
+    for (int column = 0; column < n; column++)
+    {
+        dp[0][column] = 1;
+    }
+
+    for (int row = 1; row < m; row++)
+    {
+        dp[row][0] = 1;
+    }
+
+    for (int row = 1; row < m; row++)
+    {
+        for (int column = 1; column < n; column++)
+        {
+            dp[row][column] = dp[row - 1][column] + dp[row][column - 1];
+        }
+    }
+    return dp[m - 1][n - 1];
+}