Problems

add-two-numbers

alternating-characters

balanced-binary-tree

balanced-lineup

best-time-to-buy-and-sell-stock-ii

best-time-to-buy-and-sell-stock-iii

best-time-to-buy-and-sell-stock

binary-representation

binary-search-tree-iterator

binary-tree-inorder-traversal

binary-tree-level-order-traversal-ii

binary-tree-level-order-traversal

binary-tree-maximum-path-sum

binary-tree-path-sum

binary-tree-paths

binary-tree-postorder-traversal

binary-tree-preorder-traversal

binary-tree-zigzag-level-order-traversal

chocolate-feast

circular-array-rotation

climbing-stairs

clone-binary-tree

coins-in-a-line

combination-sum-ii

combination-sum-iv

combination-sum

compare-strings

construct-binary-tree-from-inorder-and-postorder-traversal

construct-binary-tree-from-preorder-and-inorder-traversal

container-with-most-water

continuous-subarray-sum

convert-binary-search-tree-to-sorted-doubly-linked-list

convert-sorted-array-to-binary-search-tree-with-minimal-height

convert-sorted-list-to-balanced-bst

copy-list-with-random-pointer

cosine-similarity

count-1-in-binary

data-stream-median

delete-node-in-the-middle-of-singly-linked-list

design-add-and-search-words-data-structure

distinct-subsequences

evaluate-reverse-polish-notation

find-minimum-in-rotated-sorted-array-ii

find-minimum-in-rotated-sorted-array

find-peak-element

find-the-missing-number

first-bad-version

first-missing-positive

first-position-of-target

flatten-binary-tree-to-linked-list

game-of-thrones

generate-parentheses

graph-valid-tree

halloween-party

house-robber-ii

house-robber-iii

implement-queue-by-two-stacks

implement-strstr

implement-trie-prefix-tree

insert-interval

insert-node-in-a-binary-search-tree

insertion-sort-list

integer-to-roman

interleaving-positive-and-negative-numbers

interleaving-string

intersection-of-two-arrays-ii

intersection-of-two-arrays

intersection-of-two-linked-lists

interval-minimum-number

invert-binary-tree

kth-largest-element

kth-smallest-number-in-sorted-matrix

length-of-last-word

letter-combinations-of-a-phone-number

linked-list-cycle-ii

linked-list-cycle

longest-common-prefix

longest-common-subsequence

longest-common-substring

longest-consecutive-sequence

longest-increasing-continuous-subsequence

longest-increasing-subsequence

longest-palindromic-substring

longest-substring-without-repeating-characters

lowest-common-ancestor-of-a-binary-tree

manasa-and-stones

majority-number

majority-number-ii

majority-number-iii

matrix-zigzag-traversal

max-points-on-a-line

maximum-depth-of-binary-tree

maximum-product-subarray

maximum-subarray-difference

maximum-subarray-ii

maximum-subarray

merge-intervals

merge-k-sorted-lists

merge-sorted-array

merge-two-sorted-arrays

merge-two-sorted-lists

minimum-adjustment-cost

minimum-depth-of-binary-tree

minimum-path-sum

minimum-size-subarray-sum

minimum-subarray

mock-hanoi-tower-by-stacks

next-permutation

nth-to-last-node-in-list

number-of-airplanes-in-the-sky

number-of-islands

o1-check-power-of-2

palindrome-linked-list

palindrome-partitioning

partition-array-by-odd-and-even

partition-array

permutation-index

permutation-sequence

permutations-ii

previous-permutation

print-numbers-by-recursion

product-of-array-exclude-itself

recover-rotated-sorted-array

remove-duplicates-from-sorted-array-ii

remove-duplicates-from-sorted-array

remove-duplicates-from-sorted-list-ii

remove-duplicates-from-sorted-list

remove-linked-list-elements

remove-node-in-binary-search-tree

remove-nth-node-from-end-of-list

repeated-dna-sequences

restore-ip-addresses

reverse-integer

reverse-linked-list-ii

reverse-linked-list

reverse-nodes-in-k-group

reverse-words-in-a-string

roman-to-integer

route-between-two-nodes-in-graph

search-a-2d-matrix-ii

search-a-2d-matrix

search-for-a-range

search-in-rotated-sorted-array-ii

search-in-rotated-sorted-array

search-insert-position

search-range-in-binary-search-tree

segment-tree-build-ii

segment-tree-build

segment-tree-modify

segment-tree-query-ii

segment-tree-query

serialize-and-deserialize-binary-tree

set-matrix-zeroes

sherlock-and-gcd

sherlock-and-permutations

sherlock-and-squares

sherlock-and-the-beast

shortest-unique-prefix

single-number-ii

single-number-iii

sort-integers-ii

sort-letters-by-case

space-replacement

spiral-matrix-ii

string-permutation

sum-of-two-integers

super-ugly-number

surrounded-regions

swap-nodes-in-pairs

swap-two-nodes-in-linked-list

the-love-letter-mystery

the-quickest-way-up

the-skyline-problem

the-smallest-difference

topological-sorting

trapping-rain-water

two-strings-are-anagrams

unbounded-knapsack

unique-binary-search-trees-ii

unique-binary-search-trees

unique-characters

unique-paths-ii

valid-palindrome

valid-parentheses

validate-binary-search-tree

word-count-map-reduce

Roman to Integer

Problem

Given a roman numeral, convert it to an integer.

The answer is guaranteed to be within the range from 1 to 3999.

Example

IV -> 4
XII -> 12
XXI -> 21
XCIX -> 99

Note

What is Roman Numeral?

Online Judge

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