Minimum_Watering_Kits.cpp

// In a garden, there is a row of plants. The gardener need to water them regularly.
// In the row of plants, some are empty places some are plants. you need to setup 
// the watering kits to water the row of plants at the empty places. A watering kit
// can supply water to its adjacent plants, i.e., if the watering kit is at 
// i-th position it can water the plants ar 'i+1'-th and 'i-1'-th  positions.

// You are given a string 'plants', consists of two characters only [P,E], where P 
// indiactes plant and E indicates empty place.

// Your task is to return the minimum number of watering kits needed so that 
// for every plant, the gardener can supply the water to all the plants in that 
// row OR -1 if it is impossible.


// Input Format:
// -------------
// A string, consists of only two characters P and E

// Output Format:
// --------------
// Print an integer result, the minimum num of watering kits.


// Sample Input-1:
// ---------------
// PEEEPEP

// Sample Output-1:
// ----------------
// 2

// Explanation: 
// ------------
// You can setup watering kits at index-1, index-5, so all the 3 plants gets water.


// Sample Input-2:
// ---------------
// PEPEEPP

// Sample Output-2:
// ----------------
// -1

// Explanation: 
// ------------
// No empty place after the last plant in the row, so retrun -1.




#include<bits/stdc++.h>
using namespace std;
int main(){
    string s;
    cin>>s;
    int c=0;
    for(int i=1;i<s.size()-1;i++){
        if(s[i]=='E'){
            if(s[i-1]=='P' && s[i+1]=='P'){
                s[i-1]='*';
                s[i+1]='*';
                c++;
            }
        }
    }
    for(int i=0;i<s.size();i++){
        if(s[i]=='P'){
            if(i==0 && s[i+1]=='E'){
                c++;
            }
            else if(i==s.size()-1 && s[i-1]=='E'){
                c++;
            }
            else if(i>0 && i<s.size()-1 && s[i-1]=='E' || s[i+1]=='E'){
                c++;
            }
            else{
                cout<<-1;
                exit(0);
            }
        }
    }
    cout<<c;
}