Question

Write a generic function int find_lower_bound(T seq[], int n, const T& value). The function returns the index of the largest element in the given sequence that is less than the given value. If multiple elements satisfy, return the one with smallest index. Return -1 if no such element exists.

//main.cpp

#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;

#include "source.h"

struct Point{
   int x,y;
   bool operator<(const Point& p) {
       return (x<p.x || (x==p.x&&y<p.y));
   }
};

int main()
{
   //freopen("test01.in", "r", stdin);
   //freopen("test01.out", "w", stdout);

   {
   int A[5] = { 2, 10, 8, 6, 9 };
   cout<<find_lower_bound(A, 5, 9)<<endl;
   }
   {
   int A[5] = { 2, 10, 8, 2, 9 };
   cout<<find_lower_bound(A, 5, 3)<<endl;
   }
   {
   int A[5] = { 2, 1, 2, 6, 9 };
   cout<<find_lower_bound(A, 5, 1)<<endl;
   }

   double B[5] = { 3.0, 4.5, 6.0, 5.1, 1.3 };
   cout<<find_lower_bound(B, 5, 5.2)<<endl;

   Point C[5] = { {1,2},{2,3},{4,5},{1,3},{2,4}};
   Point c={3,2};
   cout<<find_lower_bound(C,5,c)<<endl;

   return 0;
}

Answer 1

int find_lower_bound(T seq[], int n, const T& value)//method finds largest element less than the value
{
   int max,f=0;
   for(int i=0;i<n;i++)
   {
       if(f==0)
       {
           if(a[i]<value)
           {
               f=1;
               max=a[i];  
           }  
       }
       else
       {
           if(max<a[i] && a[i]<value)//updating max if less than the value
           max=a[i];  
       }  
          
   }
   if(f==0)return -1;
   return max;
}