solved Competitive-Coding-2

Problem1.java

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+// Time Complexity: O(m*n)
+// SpaceComplexity: O(m*n)
+class Knapsack {
+    public int knapsack(int W, int val[], int wt[]) {
+
+        int m= wt.length;
+        int n = W;
+
+        int [][] dp = new int [m+1][n+1];
+
+        for(int i = 1; i<=m; i++){
+            int weight = wt[i-1];
+            for(int j= 0; j<=n; j++) {
+                if(j < weight) {
+                    dp[i][j] = dp[i-1][j];
+                } else {
+                    dp[i][j] = Math.max(dp[i-1][j], val[i-1]+dp[i-1][j-weight]);
+                }
+            }
+        }
+        return dp[m][n];
+    }
+}

Problem2.java

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+// Time Complexity: O(n)
+// SpaceComplexity: O(n)
+class Solution {
+    public int[] twoSum(int[] nums, int target) {
+        HashMap<Integer, Integer> map = new HashMap<>();
+        for (int i =0; i< nums.length; i++){
+            int diff = target - nums[i];
+            if(map.containsKey(diff)){
+                return new int[] {i, map.get(diff)};
+            } else {
+                map.put(nums[i],i);
+            }
+        }
+        return new int[2];
+    }
+}