Commit 534f5ca

author

Tushar Roy

committed

add map method for longest substring with k distiinct characters

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Lines changed: 39 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,8 @@`
`1`	`1`	`package com.interview.string;`
`2`	`2`
	`3`	`+import java.util.HashMap;`
	`4`	`+import java.util.Map;`
	`5`	`+`
`3`	`6`	`/**`
`4`	`7`	`* Date 04/03/2016`
`5`	`8`	`* @author Tushar Roy`
`@@ -42,4 +45,40 @@ public int lengthOfLongestSubstringKDistinct(String s, int k) {`
`42`	`45`	`}`
`43`	`46`	`return max;`
`44`	`47`	`}`
	`48`	`+`
	`49`	`+ public int lengthOfLongestSubstringKDistinctUsingMap(String s, int k) {`
	`50`	`+ if (k == 0 \|\| s.length() == 0) {`
	`51`	`+ return 0;`
	`52`	`+ }`
	`53`	`+ Map<Character, Integer> countMap = new HashMap<>();`
	`54`	`+ int max = 0;`
	`55`	`+ int start = 0;`
	`56`	`+ for (int i = 0; i < s.length(); i++) {`
	`57`	`+ char ch = s.charAt(i);`
	`58`	`+ if (!countMap.containsKey(ch) && countMap.size() >= k) {`
	`59`	`+ while (start < i) {`
	`60`	`+ countMap.compute(s.charAt(start), (key, val) -> {`
	`61`	`+ if (val == 1) {`
	`62`	`+ return null;`
	`63`	`+ } else {`
	`64`	`+ return val - 1;`
	`65`	`+ }`
	`66`	`+ });`
	`67`	`+ start++;`
	`68`	`+ if (countMap.size() < k) {`
	`69`	`+ break;`
	`70`	`+ }`
	`71`	`+ }`
	`72`	`+ }`
	`73`	`+ countMap.compute(ch, (key, val) -> {`
	`74`	`+ if (val == null) {`
	`75`	`+ return 1;`
	`76`	`+ } else {`
	`77`	`+ return val + 1;`
	`78`	`+ }`
	`79`	`+ });`
	`80`	`+ max = Math.max(max, i - start + 1);`
	`81`	`+ }`
	`82`	`+ return max;`
	`83`	`+ }`
`45`	`84`	`}`

Lines changed: 4 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -12,5 +12,9 @@ public void testDifferenceCases() {`
`12`	`12`	`Assert.assertEquals(1, longestSubstringWithKDistinctCharacters.lengthOfLongestSubstringKDistinct("aba", 1));`
`13`	`13`	`Assert.assertEquals(5, longestSubstringWithKDistinctCharacters.lengthOfLongestSubstringKDistinct("caebegcle", 4));`
`14`	`14`	`Assert.assertEquals(0, longestSubstringWithKDistinctCharacters.lengthOfLongestSubstringKDistinct("eceba", 0));`
	`15`	`+ Assert.assertEquals(3, longestSubstringWithKDistinctCharacters.lengthOfLongestSubstringKDistinctUsingMap("eceba", 2));`
	`16`	`+ Assert.assertEquals(1, longestSubstringWithKDistinctCharacters.lengthOfLongestSubstringKDistinctUsingMap("aba", 1));`
	`17`	`+ Assert.assertEquals(5, longestSubstringWithKDistinctCharacters.lengthOfLongestSubstringKDistinctUsingMap("caebegcle", 4));`
	`18`	`+ Assert.assertEquals(0, longestSubstringWithKDistinctCharacters.lengthOfLongestSubstringKDistinctUsingMap("eceba", 0));`
`15`	`19`	`}`
`16`	`20`	`}`

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