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@spannm
spannm committed Jul 4, 2024
1 parent d9714b6 commit ffe16bf
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4 changes: 2 additions & 2 deletions src/main/java/io/github/spannm/leetcode/lc0/lc0000/Problem0001.java
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Expand Up @@ -55,11 +55,11 @@ static final class IdxAndNum {
num = _num;
}

public int getIdx() {
int getIdx() {
return idx;
}

public int getNum() {
int getNum() {
return num;
}

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29 changes: 4 additions & 25 deletions src/main/java/io/github/spannm/leetcode/lc0/lc0000/Problem0011.java
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Expand Up @@ -8,40 +8,19 @@
class Problem0011 extends LeetcodeProblem {

int maxArea(final int[] _height) {
return maxAreaOptimized(_height);
}

public int maxAreaNaive(final int[] _height) {
int minHeight = 0;
int area = 0;
int maxArea = 0;

for (int x1 = _height.length - 1; x1 >= 0; x1--) {
for (int x2 = 0; x2 < x1; x2++) {
minHeight = Math.min(_height[x1], _height[x2]);
area = minHeight * (x1 - x2);
if (area > maxArea) {
maxArea = area;
}
}
}
return maxArea;
}

public int maxAreaOptimized(final int[] _height) {
int idxL = 0;
int idxR = _height.length - 1;
int hL = 0;
int hR = 0;
int area = 0;
int maxArea = 0;
int maxArea1 = 0;

while (idxL < idxR) {
hL = _height[idxL];
hR = _height[idxR];
area = Math.min(hL, hR) * (idxR - idxL);
if (area > maxArea) {
maxArea = area;
if (area > maxArea1) {
maxArea1 = area;
}

if (hL < hR) {
Expand All @@ -54,7 +33,7 @@ public int maxAreaOptimized(final int[] _height) {
}
}
}
return maxArea;
return maxArea1;
}

}
73 changes: 3 additions & 70 deletions src/main/java/io/github/spannm/leetcode/lc0/lc0000/Problem0012.java
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Expand Up @@ -2,28 +2,14 @@

import io.github.spannm.leetcode.LeetcodeProblem;

import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

/**
* <a href="https://leetcode.com/problems/integer-to-roman/">12. Integer to Roman</a>.
*/
class Problem0012 extends LeetcodeProblem {

static final Map<Integer, String> MAP = IntStream.range(1, 4000).boxed().collect(Collectors.toMap(k -> k, Problem0012::intToRomanSwitch));

public String intToRoman(final int _num) {
return intToRomanStaticMap(_num);
}

static String intToRomanStaticMap(final int _num) {
return MAP.get(_num);
}

static String intToRomanSwitch(final int _num) {
final int[] digits = {_num / 1000, _num / 100 % 10, _num / 10 % 10, _num % 10};
final StringBuilder sb = new StringBuilder();
String intToRoman(final int _num) {
int[] digits = {_num / 1000, _num / 100 % 10, _num / 10 % 10, _num % 10};
StringBuilder sb = new StringBuilder();
for (int i = 0; i < digits.length; i++) {
if (digits[i] < 1) {
continue;
Expand Down Expand Up @@ -80,57 +66,4 @@ static String intToRomanSwitch(final int _num) {
return sb.toString();
}

static String intToRomanSubtraction(int _num) {
final StringBuilder sb = new StringBuilder();
while (_num >= 1000) {
sb.append('M');
_num -= 1000;
}
if (_num >= 900) {
sb.append("CM");
_num -= 900;
} else if (_num >= 500) {
sb.append('D');
_num -= 500;
}
if (_num >= 400) {
sb.append("CD");
_num -= 400;
} else {
while (_num >= 100) {
sb.append('C');
_num -= 100;
}
}
if (_num >= 90) {
sb.append("XC");
_num -= 90;
} else if (_num >= 50) {
sb.append('L');
_num -= 50;
} else if (_num >= 40) {
sb.append("XL");
_num -= 40;
}
while (_num >= 10) {
sb.append('X');
_num -= 10;
}
if (_num == 9) {
sb.append("IX");
return sb.toString();
} else if (_num == 4) {
sb.append("IV");
return sb.toString();
} else if (_num >= 5) {
sb.append('V');
_num -= 5;
}
while (_num >= 1) {
sb.append('I');
_num -= 1;
}
return sb.toString();
}

}
34 changes: 2 additions & 32 deletions src/main/java/io/github/spannm/leetcode/lc0/lc0000/Problem0015.java
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Expand Up @@ -9,8 +9,8 @@
*/
class Problem0015 extends LeetcodeProblem {

List<List<Integer>> threeSum2(int[] _nums) {
final int len = _nums.length;
List<List<Integer>> threeSum(int[] _nums) {
int len = _nums.length;
if (len == 0) {
return List.of();
}
Expand Down Expand Up @@ -38,34 +38,4 @@ List<List<Integer>> threeSum2(int[] _nums) {
return new ArrayList<>(set);
}

public List<List<Integer>> threeSum(int[] _nums) {
List<Integer> input = Arrays.stream(_nums).sorted().boxed().toList();
final int len = input.size();
if (len < 3) {
return List.of();
}

Set<List<Integer>> results = new HashSet<>();
for (int first = 0; first < len - 2; first++) {
int second = first + 1;
int third = len - 1;
int sum;
while (second < third) {
sum = input.get(first) + input.get(second) + input.get(third);
if (sum == 0) {
results.add(List.of(input.get(first), input.get(second), input.get(third)));
second++;
third--;
} else if (sum < 0) {
second++;
} else {
third--;
}
}

}

return new ArrayList<>(results);
}

}
52 changes: 5 additions & 47 deletions src/main/java/io/github/spannm/leetcode/lc0/lc0000/Problem0017.java
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Expand Up @@ -2,31 +2,25 @@

import io.github.spannm.leetcode.LeetcodeProblem;

import java.util.*;
import java.util.stream.IntStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;

/**
* <a href="https://leetcode.com/problems/letter-combinations-of-a-phone-number/">17. Letter Combinations of a Phone
* Number</a>.
*/
class Problem0017 extends LeetcodeProblem {

@SuppressWarnings("unchecked")
private static final List<String>[] DIGITS_TO_LETTERS = new List[] {null, // 0
null, // 1
List.of("a", "b", "c"), // 2
List.of("d", "e", "f"), // 3
List.of("g", "h", "i"), List.of("j", "k", "l"), List.of("m", "n", "o"), List.of("p", "q", "r", "s"), List.of("t", "u", "v"), List.of("w", "x", "y", "z")
};

private static final char[][] DIGITS_TO_CHARS = new char[][] {null, // 0
null, // 1
{'a', 'b', 'c'}, // 2
{'d', 'e', 'f'}, // 3
{'g', 'h', 'i'}, {'j', 'k', 'l'}, {'m', 'n', 'o'}, {'p', 'q', 'r', 's'}, {'t', 'u', 'v'}, {'w', 'x', 'y', 'z'}
};

public List<String> letterCombinations(String _digits) {
List<String> letterCombinations(String _digits) {
if (_digits == null || _digits.isEmpty()) {
return List.of();
}
Expand All @@ -48,40 +42,4 @@ static Collection<String> cartesianProduct(String _input, StringBuilder _sb, int
return _product;
}

public List<String> letterCombinations2(String _digits) {
final int len = _digits.length();

if (len == 0) {
return List.of();
}

List<List<String>> lol = IntStream.range(0, len)
// .map(i -> digits.charAt(i) - '0')
.map(i -> Character.getNumericValue(_digits.charAt(i)))
.mapToObj(i -> DIGITS_TO_LETTERS[i])
.toList();

if (len == 1) {
return lol.get(0);
}

Set<String> combinations = new LinkedHashSet<>();

generatePermutations(lol, combinations, 0, "");

return new ArrayList<>(combinations);
}

// cartesian product
void generatePermutations(List<List<String>> _lists, Collection<String> _result, int _depth, String _current) {
if (_depth == _lists.size()) {
_result.add(_current);
return;
}

for (String element : _lists.get(_depth)) {
generatePermutations(_lists, _result, _depth + 1, _current + element);
}
}

}
33 changes: 4 additions & 29 deletions src/main/java/io/github/spannm/leetcode/lc0/lc0000/Problem0018.java
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Expand Up @@ -2,41 +2,17 @@

import io.github.spannm.leetcode.LeetcodeProblem;

import java.util.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.LongStream;

/**
* <a href="https://leetcode.com/problems/4sum/">18. 4Sum</a>.
*/
class Problem0018 extends LeetcodeProblem {

List<List<Integer>> fourSum1(int[] _nums, int _target) {
final int len = _nums.length;
Arrays.sort(_nums);

Set<List<Integer>> sets = new HashSet<>();
for (int i = 0; i < len - 3; i++) {
for (int j = i + 1; j < len - 2; j++) {
for (int k = j + 1; k < len - 1; k++) {
for (int p = k + 1; p < len; p++) {
int sum = _nums[i] + _nums[j] + _nums[k] + _nums[p];
if (sum == _target) {
sets.add(List.of(_nums[i], _nums[j], _nums[k], _nums[p]));
}
}
}
}
}

List<List<Integer>> results = new ArrayList<>(sets);

_nums = null;
sets = null;

return results;
}

public List<List<Integer>> fourSum(int[] _nums, final int _target) {
List<List<Integer>> fourSum(int[] _nums, final int _target) {
final int len = _nums.length;
if (len <= 4) {
if (len == 4 && Arrays.stream(_nums).mapToLong(i -> i).sum() == _target) {
Expand Down Expand Up @@ -88,7 +64,6 @@ public List<List<Integer>> fourSum(int[] _nums, final int _target) {
}
}
}
nums = null;
return results;
}

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37 changes: 0 additions & 37 deletions src/main/java/io/github/spannm/leetcode/lc0/lc0000/Problem0020.java
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Expand Up @@ -28,41 +28,4 @@ boolean isValid(String _s) {
return stack.isEmpty();
}

public boolean isValid2(String _s) {
if (_s.length() % 2 != 0) {
return false;
}

final char[] charArray = _s.toCharArray();
final char[] stack = new char[charArray.length];
int head = 0;
for (char c : charArray) {
switch (c) {
case '{':
case '[':
case '(':
stack[head++] = c;
continue;
case '}':
if (head == 0 || stack[--head] != '{') {
return false;
}
break;
case ')':
if (head == 0 || stack[--head] != '(') {
return false;
}
break;
case ']':
if (head == 0 || stack[--head] != '[') {
return false;
}
break;
default:
break;
}
}
return head == 0;
}

}
2 changes: 1 addition & 1 deletion src/main/java/io/github/spannm/leetcode/lc0/lc0000/Problem0024.java
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Expand Up @@ -8,7 +8,7 @@
*/
class Problem0024 extends LeetcodeProblem {

static ListNode swapPairs(ListNode _head) {
ListNode swapPairs(ListNode _head) {
if (_head == null || _head.next == null) {
return _head;
}
Expand Down
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