add Unique Paths solution

Author: HoonDongKang

unique-paths/HoonDongKang.ts

@@ -0,0 +1,69 @@
+/**
+ * [Problem]: [62] Unique Paths
+ * (https://leetcode.com/problems/unique-paths/description/)
+ */
+
+function uniquePaths(m: number, n: number): number {
+    //시간복잡도 O(2^(m*n))
+    //공간복잡도 O(m*n)
+    // Time Limit Exceeded
+    function dfsFunc(m: number, n: number): number {
+        let result: number = 0;
+        function dfs(row: number, col: number) {
+            if (row === m - 1 && col === n - 1) result++;
+            if (row + 1 < m) dfs(row + 1, col);
+            if (col + 1 < n) dfs(row, col + 1);
+        }
+
+        dfs(0, 0);
+        return result;
+    }
+
+    //시간복잡도 O(m*n)
+    //공간복잡도 O(m*n)
+    function memoizationFunc(m: number, n: number): number {
+        let memo = new Map<string, number>();
+
+        function dfs(row: number, col: number) {
+            const key = `${row}|${col}`;
+
+            if (memo.has(key)) return memo.get(key);
+            if (row === m - 1 && col === n - 1) return 1;
+            if (row >= m || col >= n) return 0;
+
+            const result = dfs(row + 1, col) + dfs(row, col + 1);
+
+            memo.set(key, result);
+            return result;
+        }
+
+        return dfs(0, 0);
+    }
+    //시간복잡도 O(m*n)
+    //공간복잡도 O(m*n)
+    function dpFunc(m: number, n: number): number {
+        let dp: number[][] = Array.from({ length: m }, () => Array(n).fill(1));
+
+        for (let i = 1; i < m; i++) {
+            for (let j = 1; j < n; j++) {
+                dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
+            }
+        }
+
+        return dp[m - 1][n - 1];
+    }
+    //시간복잡도 O(m*n)
+    //공간복잡도 O(n)
+    function optimizationFunc(m: number, n: number): number {
+        let dp: number[] = new Array(n).fill(1);
+        for (let i = 1; i < m; i++) {
+            let left = 1;
+            for (let j = 1; j < n; j++) {
+                dp[j] += left;
+                left = dp[j];
+            }
+        }
+
+        return dp[n - 1];
+    }
+}