# Integer to Roman conversion - Leet Code Solution

September 13, 2019

## Problem Statement

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

``````Symbol       Value
I             1
V             5
X             10
L             50
C             100
D             500
M             1000``````

For example, two is written as II in Roman numeral, just two one’s added together. Twelve is written as, XII, which is simply X + II. The number twenty seven is written as XXVII, which is XX + V + II.

Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IIII. Instead, the number four is written as IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX. There are six instances where subtraction is used:

``````I can be placed before V (5) and X (10) to make 4 and 9.
X can be placed before L (50) and C (100) to make 40 and 90.
C can be placed before D (500) and M (1000) to make 400 and 900.``````

Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999.

## Solution

The question looks simple interms that we need to keep mappings. There are three special cases i.e. where subtraction is used.

Lets look at the code:

``````public String intToRoman(int num) {
Map<Integer, String> map = new HashMap();
map.put(1, "I"); map.put(5, "V"); map.put(10, "X");
map.put(50, "L"); map.put(100, "C"); map.put(500, "D"); map.put(1000, "M");
map.put(4, "IV"); map.put(9, "IX"); map.put(40, "XL"); map.put(90, "XC");
map.put(400, "CD"); map.put(900, "CM");

int[] sequence = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};

StringBuffer sb = new StringBuffer();
for (int i=0; i<sequence.length; i++) {
int base = sequence[i];

while (num >= base) {
sb.append(map.get(base));
num -= base;
}
}

return sb.toString();
}``````

## Similar Posts

### Bubble Sort Algorithm

This is kind of preliminary technique of sorting. And, this is the first…

### Validate Sudoku - Leet Code Solution

Problem Statement Determine if a 9x9 Sudoku board is valid. Only the filled…

### Check whether an integer number given is palindrome or not - Leet Code Solution

Problem Statement Determine whether an integer is a palindrome. An integer is a…

### Max Priority Queue Implementation with Heap Data structure

Max Priority Queue is a data structure which manage a list of keys(values). And…

### Swap Nodes Pairs in Link List - Leet Code Solution

Problem Statement Given a linked list, swap every two adjacent nodes and return…

### Reverse digits of a signed integer - Leet Code Solution

Problem Statement Given a signed integer, reverse digits of an integer. Return…

## Latest Posts

### Jenkins Pipeline with Jenkinsfile - How To Schedule Job on Cron and Not on Code Commit

Introduction In this post we will see following: How to schedule a job on cron…

### How to Git Clone Another Repository from Jenkin Pipeline in Jenkinsfile

Introduction There are some cases, where I need another git repository while…

### How to Fetch Multiple Credentials and Expose them in Environment using Jenkinsfile pipeline

Introduction In this post, we will see how to fetch multiple credentials and…

### Jenkins Pipeline - How to run Automation on Different Environment (Dev/Stage/Prod), with Credentials

Introduction I have an automation script, that I want to run on different…

### Jenkinsfile - How to Create UI Form Text fields, Drop-down and Run for Different Conditions

Introduction I had to write a CICD system for one of our project. I had to…

### Java Log4j Logger - Programmatically Initialize JSON logger with customized keys in json logs

Introduction Java log4j has many ways to initialize and append the desired…