116 lines
3.1 KiB
Java
116 lines
3.1 KiB
Java
package Misc;
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import java.util.*;
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import java.util.stream.Collectors;
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public class TwoSumProblem {
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public static void main(String args[])
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{
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Scanner scan = new Scanner(System.in);
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System.out.print("Enter the target sum ");
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int ts= scan.nextInt();
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System.out.print("Enter the number of elements in the array ");
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int n = scan.nextInt();
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System.out.println("Enter all your array elements:");
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int arr[]= new int[n];
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for(int i=0;i<n;i++)
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{
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arr[i]=scan.nextInt();
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}
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TwoSumProblem t = new TwoSumProblem();
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System.out.println("Brute Force Approach\n"+Arrays.toString(t.BruteForce(arr,ts))+"\n");
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System.out.println("Two Pointer Approach\n"+Arrays.toString(t.TwoPointer(arr,ts))+"\n");
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System.out.println("Hashmap Approach\n"+Arrays.toString(t.HashMap(arr,ts)));
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}
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public int[] BruteForce(int[] nums, int target) {
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//Brute Force Approach
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int ans[]=new int[2];
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for (int i=0;i<nums.length;i++)
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{
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for (int j=i+1;j<nums.length;j++)
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{
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if(nums[i]+nums[j]==target)
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{
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ans[0]=i;
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ans[1]=j;
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break;
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}
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}
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}
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return ans;
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}
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public int[] TwoPointer(int[] nums, int target) {
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// HashMap Approach
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int ans[]=new int[2];
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HashMap<Integer,Integer> hm=new HashMap<Integer,Integer>();
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for(int i =0;i<nums.length;i++)
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{
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hm.put(i,nums[i]);
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}
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HashMap<Integer, Integer> temp
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= hm.entrySet()
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.stream()
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.sorted((i1, i2)
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-> i1.getValue().compareTo(
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i2.getValue()))
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.collect(Collectors.toMap(
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Map.Entry::getKey,
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Map.Entry::getValue,
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(e1, e2) -> e1, LinkedHashMap::new));
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int start = 0;
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int end = nums.length - 1;
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while (start<end)
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{ int currSum=(Integer) temp.values().toArray()[start]+(Integer) temp.values().toArray()[end];
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if(currSum==target)
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{
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ans[0]=(Integer) temp.keySet().toArray()[start];
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ans[1]=(Integer) temp.keySet().toArray()[end];
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break;
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}
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else if(currSum>target)
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end-=1;
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else if(currSum<target)
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{
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start+=1;
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}
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}
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return ans;
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}
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public int[] HashMap(int[] nums, int target) {
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//Using Hashmaps
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int ans[]=new int[2];
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HashMap<Integer,Integer> hm=new HashMap<Integer,Integer>();
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for(int i=0;i<nums.length;i++)
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{
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hm.put(nums[i],i);
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}
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for(int i =0;i<nums.length;i++)
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{
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int t = target - nums[i];
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if(hm.containsKey(t) && hm.get(t)!=i)
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{
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ans[0]=i;
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ans[1]=hm.get(t);
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break;
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}
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}
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return ans;
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}
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}
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