Mentor Session Vikas Sharma

Original Session

Date: 21 Dec 2024

1. Sum of two numbers without using arithmetic operators
   1. GFG here

   int sum(int a , int b)
       {
           //code here
           
           while (b != 0) {
               int carry = (a&b)<<1;
               a = a^b;
               b = carry;    
           }
           
           return a;
       }

2. Search in a Row-Column sorted matrix, solve in O(n)
   1. GFG here

   static boolean matSearch(int mat[][], int x) {
           // your code here
           
           int row = 0, col = mat[0].length-1;
           
           while (col > -1 && row < mat.length) {
               
               if (x > mat[row][col]) {
                   row ++;
               } else if (x < mat[row][col]) {
                   col --;
               } else {
                   return true;
               }
           }
           
           return false;
       }

3. unsorted array, Find two indexes such that, arr[i] - arr[j] == k, k is target

   static void towSumAMinusBEqK(int[] nums, int k) {
           
           // i -j = k, k+j = i;
           // [-1,2,5,8,-3], k=3
           Map<Integer, Integer> map = new HashMap();
           
           for (int i=0; i< nums.length; i++) {
               map.put(nums[i], i);
           }
           
           for (int i=0; i< nums.length; i++) {
               
               int sub = k+nums[i];
               if (!map.containsKey(sub)) {
                   map.put(nums[i], i);
                   continue;
               }
               
               int j = map.get(sub);
               System.out.print(" i " + i + " j " + j);
               break;
           } 
       }