Arrayfirstpart.java

import java.util.*;
public class Arrayfirstpart {

    // passing array as argument
      public static void update(int marks[]){
        for(int i = 0;i<marks.length;i++){  // going to each element of array
            marks[i]=marks[i]+1;
        }
    }
    //  linear search
    public static int  linearSearch(int num[],int key) {
        for(int i =0;i<num.length;i++){
            if(num[i]==key){
                return i;
            }
        }
         return -1;
    }

    // largest number
    public static int largest(int numbers[]){
        int ln = Integer.MIN_VALUE; // -infinity

        for(int i = 0; i<numbers.length;i++){
            if(ln< numbers[i]){
                ln = numbers[i];
            }
        }
        return ln;
    }


    // binary search
    public static int binsearch(int numbers[],int key){
        int start = 0, end = numbers.length-1;

        while(start<= end){
            int mid = (start+end)/2;

            // comparison
            if(numbers[mid]==key){
                return mid; 

            }if(numbers[mid]<key){
                start = mid+1;
            }else{
                end = mid-1;
            }
        }
        return -1;
    }


    // Reverse an array
    public static void reverse(int number[]){
        int first=0,last = number.length-1;
        while(first<last){
            // Swapping 
            int temp = number[last];
            number[last]=number[first];
            number[first]=temp;

        first++;
        last--;
        }
    }

    // pairs in array
    public static void pairs(int num[]){
        for(int i =0;i<num.length;i++){
            int curr = num[i];
            for(int j = i+1;j<num.length;j++){
                System.out.println(curr+","+num[j]);
            }
            System.out.println();
        }
    }

    // subarrays print
    public static void subarray(int num[]){
        int ts=0;
        for(int i = 0; i<num.length;i++){
            int start = i;
            for(int j=i;j<num.length;j++){
                int end = j;
                for(int k =start;k<=end;k++){
                    System.out.print(num[k]+""); //subarray
                }
                ts++;
                System.out.println();
            }
            System.out.println();
        }
        System.out.println("total subarray--"+ts);
    } 
    //  subarray maximum sum
    public static void subarraysum(int num[]){
        int maxsum=Integer.MIN_VALUE,currentsum=0;
        for(int i = 0; i<num.length;i++){
            int start = i;
            for(int j=i;j<num.length;j++){
                int end = j;
                currentsum=0;
                for(int k =start;k<=end;k++){
                    currentsum+=num[k];
                   
                }if(maxsum<currentsum){
                    maxsum = currentsum;
                    
                }
            }
        }
        System.out.println(maxsum); 
    } 

    // prefix sum
    public static void subarrayprefixsum(int num[]){
        int maxsum=Integer.MIN_VALUE,currentsum=0;
        int prefix []= new int[num.length];
        prefix[0]=num[0];
         
        // calculate prefix array
        for(int i =1;i<prefix.length;i++){
            prefix[i]=prefix[i-1]+num[i];
        }

          
        for(int i = 0; i<num.length;i++){
            int start = i;
            for(int j=i;j<num.length;j++){
                int end = j;
                currentsum= start==0? prefix[end]:prefix[end]-prefix[start-1]; //curent sum 
                
                   
                }if(maxsum<currentsum){
                    maxsum = currentsum;
                    
                }
            }
        
        System.out.println(maxsum); 
    } 
    

    // kadnes algorithm 
    public static void kadanes(int num[]){
        int ms=Integer.MIN_VALUE,cs=0;
        for(int i = 0;i<num.length;i++){
            cs = cs+num[i];
            if(cs<0){
                cs=0;
            }
            ms = Math.max(cs,ms);
        }
        System.out.println(ms);
    }


        public static void main(String[] args) {
        // creation of array
        // int marks[]=new int[100];
        // String fruits[] = {"banana","mango","orange"};

         //input output in array
         Scanner sc = new Scanner(System.in);
        //  marks[0]=sc.nextInt();
        //  marks[1]=sc.nextInt();
        //  marks[2]=sc.nextInt();
        //  marks[0]=marks[0]+1;  //update 

        // System.out.println(marks[0]);
        // System.out.println(marks[1]);
        // System.out.println(marks[2]);

        // System.out.println(marks.length);  //length of array

        // linear search

        // int num []= {98,99,100,40,50,60,80,10,20,30,};
        // int key = 60;
        // int index=linearSearch(num, key);
        // System.out.println(index);


        // largest number
        // int numbers[] = {10,100,40,50,70,1000,20,800,900};
        // System.out.println(largest(numbers));
       
         
        // binary search
        // int numbers[] = {10,20,27,28,29,30,40 };
        // int key = 29;
        // System.out.println(binsearch(numbers,key));
        

        // reverse in array
        // int number[] = {10,20,27,28,29,30,40 };
        // reverse(number);
        // for(int i = 0;i<number.length;i++){
        //     System.out.print(number[i]+"  ");
        // }
        // System.out.println();


        //pairs
        //  int num[] = {10,20,27,28,29,30,40 };
        //  pairs(num);
          

        // subarray
        //  int num[] = {10,20,27,28,29,30,40 };
        //  subarray(num);

        // // maximum subarray sum
        //  int num[] = {10,20,27,28,29,30,40 };
        //  subarraysum(num);

        // //  prefix sum
        //  subarrayprefixsum(num);

        int num[] = {10,20,27,28,29,30,40 };
        kadanes(num);

        sc.close(); 

    }
}