leetcode/src/leetcode/string/StringCompression.java at master · dim4o/leetcode · GitHub

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// Given an array of characters, compress it in-place.
// The length after compression must always be smaller than or equal to the original array.
// Every element of the array should be a character (not int) of length 1.
// After you are done modifying the input array in-place, return the new length of the array.
// Follow up:
// Could you solve it using only O(1) extra space?
// See: https://leetcode.com/problems/string-compression/

packageleetcode.string;

importjava.util.ArrayList;
importjava.util.List;

publicclassStringCompression {

// TODO: solve it using O(1) space (no helper array).
publicintcompress(char[] chars) {
if (chars.length == 1)
return1;

List<int[]> list = newArrayList<>();
intcount = 1;
for (inti = 0; i < chars.length - 1; i++) {
if (chars[i] == chars[i + 1])
count++;

if (chars[i] != chars[i + 1] || i == chars.length - 2) {
list.add(newint[] { chars[i], count });
count = 1;
if (chars[i] != chars[i + 1] && i == chars.length - 2)
list.add(newint[] { chars[i + 1], count });
 }

 }

intpos = 0;
for (int[] pair : list) {
chars[pos] = (char) pair[0];
count = pair[1];
if (count > 1) {
char[] digits = String.valueOf(count).toCharArray();
for (chardigit : digits) {
chars[pos + 1] = digit;
pos += 1;
 }
 }
pos += 1;
 }

// System.out.println(Arrays.toString(chars));

returnpos;
 }

publicstaticvoidmain(String[] args) {
StringCompressionsln = newStringCompression();

System.out.println(sln.compress(newchar[] { 'a', 'a', 'b', 'b', 'c', 'c', 'c' }));

System.out.println(sln.compress(newchar[] { 'a' }));

System.out.println(sln.compress(
newchar[] { 'a', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b' }));

System.out.println(sln.compress(newchar[] { 'a', 'a', 'a', 'b', 'b', 'a', 'a' }));

System.out.println(sln.compress(newchar[] { 'a', 'b', 'c' }));

 }

}