Added brute force to jump game 2

Author: gahogg

Jump Game II - Leetcode 45/Jump Game II - Leetcode 45.cpp

@@ -1,3 +1,36 @@
+// Brute Force
+#include <vector>
+#include <algorithm>
+#include <climits>
+
+class Solution {
+public:
+    int jump(std::vector<int>& nums) {
+        int n = nums.size();
+        int smallest = INT_MAX;
+
+        backtrack(0, 0, nums, n, smallest);
+        return smallest;
+    }
+
+private:
+    void backtrack(int i, int jumps, std::vector<int>& nums, int n, int& smallest) {
+        if (i == n - 1) {
+            smallest = std::min(smallest, jumps);
+            return;
+        }
+
+        int maxJump = nums[i];
+        int maxReachableIndex = std::min(i + maxJump, n - 1);
+
+        for (int newIndex = maxReachableIndex; newIndex > i; newIndex--) {
+            backtrack(newIndex, jumps + 1, nums, n, smallest);
+        }
+    }
+};
+
+
+// Optimal
 #include <vector>
 #include <algorithm>
 

Jump Game II - Leetcode 45/Jump Game II - Leetcode 45.java

@@ -1,3 +1,30 @@
+// Brute Force
+public class Solution {
+    public int jump(int[] nums) {
+        int n = nums.length;
+        int[] smallest = {Integer.MAX_VALUE};
+
+        backtrack(0, 0, nums, n, smallest);
+        return smallest[0];
+    }
+
+    private void backtrack(int i, int jumps, int[] nums, int n, int[] smallest) {
+        if (i == n - 1) {
+            smallest[0] = Math.min(smallest[0], jumps);
+            return;
+        }
+
+        int maxJump = nums[i];
+        int maxReachableIndex = Math.min(i + maxJump, n - 1);
+
+        for (int newIndex = maxReachableIndex; newIndex > i; newIndex--) {
+            backtrack(newIndex, jumps + 1, nums, n, smallest);
+        }
+    }
+}
+
+
+// Optimal
 class Solution {
     public int jump(int[] nums) {
         int smallest = 0;

Jump Game II - Leetcode 45/Jump Game II - Leetcode 45.js

@@ -1,3 +1,28 @@
+// Brute Force
+var jump = function(nums) {
+    var n = nums.length;
+    var smallest = [Infinity];
+
+    function backtrack(i, jumps) {
+        if (i === n - 1) {
+            smallest[0] = Math.min(smallest[0], jumps);
+            return;
+        }
+
+        var maxJump = nums[i];
+        var maxReachableIndex = Math.min(i + maxJump, n - 1);
+
+        for (var newIndex = maxReachableIndex; newIndex > i; newIndex--) {
+            backtrack(newIndex, jumps + 1);
+        }
+    }
+
+    backtrack(0, 0);
+    return smallest[0];
+};
+
+
+// Optimal
 var jump = function(nums) {
     var smallest = 0;
     var n = nums.length;

Jump Game II - Leetcode 45/Jump Game II - Leetcode 45.py

@@ -1,3 +1,25 @@
+# Brute Force
+class Solution:
+    def jump(self, nums: List[int]) -> int:
+        n = len(nums)
+        smallest = [float('inf')]
+
+        def backtrack(i=0, jumps=0):
+            if i == n-1:
+                smallest[0] = min(smallest[0], jumps)
+                return
+            
+            max_jump = nums[i]
+            max_reachable_index = min(i+max_jump, n-1)
+
+            for new_index in range(max_reachable_index, i, -1):
+                backtrack(new_index, jumps+1)
+        
+        backtrack()
+        return smallest[0]
+    
+    
+# Optimal    
 class Solution:
     def jump(self, nums: List[int]) -> int:
         smallest = 0