find the kth largest sum(a+b) possible where a in A, and b in B.

Given 2 Sorted arrays A, B in decreasing order of size m and n respectively and a number k, such that 1 <= k <= m*n. You need to find the kth largest sum(a+b) possible where a in A, and b in B.


Algorithm:
Take 0th index value from 1st array & 1st index value from 2nd array store it in S1
Now 0th index value from 2nd array & 1st index value from 1st array , store in S2
Also stores starting & ending index of each array -take care-off

iniatlize maxsum variable to a[0]+b[0] 
Keep checking until we found kth sum from array a & b where a is from 1st & b is from 
if s1>s2 then increment array b lastindex untill its equal to length of this array  & update maxsum=s1
else then increment array a lastindex until its equal to length of this array
maxsum=s2;

Finally Return maxsum;

2nd array.

#include<stdio.h>

int k_sum(int A[],int B[],int m,int n,int k){
	int indexA = 1;
	int indexB = 1;
	int i,s1,s2,sA=0,sB=0;
	int maxsum = A[0] + B[0];

	for(i=0;i<k-1;i++)
	{
		s1 = A[sA] + B[indexB];
		s2 = A[indexA] + B[sB];

		if(s1 >= s2){
			if(indexB == n-1){
				indexB = sB + 1;
				++sA;
			}
			else{
			++indexB;
			}
			maxsum = s1;
		}
		else{
			if(indexA == m-1){
				indexA = sA + 1;
				++sB;
			}
			else{
			++indexA;
			}
			maxsum = s2;
		}
	}

	return maxsum;
}

int main(){
	int A[5]= {10,9,6,4,3};
	int B[6] = {15,13,12,10,78,5};
	int k=10;
	printf("%d \n",k_sum(A,B,5,6,10));
		return 0;
}

Time Complexity O(K) K=M*N M,N are length of length of array s1,s2

Space Complexity O(1)

https://ideone.com/2IxZX

Run Here https://ideone.com/5Zy8B