NextSmallerElementonRight.java

#https://www.facebook.com/permalink.php?story_fbid=623985158490864&id=100026381556272
# suscribed by chandresh joshi
package com.cjwarrior7.stackandqueue;

import java.util.Stack;

public class DemoNextSmallerElementonRightAlter {
public static void main(String[] args) {
    int[] arr= new int[9];
    arr[0]=2;
    arr[1]=5;
    arr[2]=9;
    arr[3]=3;
    arr[4]=1;
    arr[5]=12;
    arr[6]=6;
    arr[7]=8;
    arr[8]=7;
    //2 5 9 3 1 12 6 8 7
    int[] res=solve(arr);
    for (int i = 0; i < res.length ; i++) {
        System.out.println(res[i]);
    }
}
public static int[] solve(int[] arr){
    int[] nge = new int[arr.length];
    Stack<Integer> st=new Stack<Integer>();
    st.push(0);
    for (int i = 1; i <arr.length ; i++) {
        while (st.size() > 0 && arr[i] < arr[st.peek()]){
            int pos=st.peek();
            nge[pos]=arr[i];
            st.pop();
        }
        st.push(i);

    }
    while (st.size()>0) {
        int pos=st.peek();
        nge[pos] = -1;
        st.pop();

    }
    return nge;
}
}