Competitive-Coding-3

KDiffPairsInAnArray.java

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+// Time Complexity :O(n)
+// Space Complexity :O(n)
+// Did this code successfully run on Leetcode :yes
+
+import java.util.HashMap;
+
+class Solution {
+    public int findPairs(int[] nums, int k) {
+        HashMap<Integer,Integer> frequency = new HashMap<>();
+        int ans=0;
+        for(int n:nums){
+            frequency.put(n,frequency.getOrDefault(n,0)+1);
+        }
+        if(k==0){
+            for(int i : frequency.values()){
+                if(i>=2)ans++;
+            }
+        }
+        else{
+            for(int j: frequency.keySet()){
+                if(frequency.containsKey(j+k))ans++;
+            }
+        }
+        return ans;
+    }
+}

Pascal'sTriangle.java

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+// Time Complexity :O(n^2)
+// Space Complexity :O(1)
+// Did this code successfully run on Leetcode :yes
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+class Solution {
+    public List<List<Integer>> generate(int numRows) {
+        List<List<Integer>> ans = new ArrayList<>();
+        ans.add(Arrays.asList(1));
+        for(int i=1;i<numRows;i++){
+            List<Integer> rowList = new ArrayList<>();
+            rowList.add(1);
+            for(int j=1;j<ans.get(i-1).size();j++){
+                rowList.add(ans.get(i-1).get(j-1)+ans.get(i-1).get(j));
+            }
+            rowList.add(1);
+            ans.add(rowList);
+        }
+        return ans;
+    }
+}