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Commit20fede4

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‎README.md

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@@ -480,6 +480,7 @@ _If you like this project, please leave me a star._ ★
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|923|[3Sum With Multiplicity](https://leetcode.com/problems/3sum-with-multiplicity/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_923.java) | |Medium|Two Pointers
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|922|[Sort Array By Parity II](https://leetcode.com/problems/sort-array-by-parity-ii/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_922.java)||Easy|
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|921|[Minimum Add to Make Parentheses Valid](https://leetcode.com/problems/minimum-add-to-make-parentheses-valid/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_921.java) | |Medium|Stack, Greedy
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|918|[Maximum Sum Circular Subarray](https://leetcode.com/problems/maximum-sum-circular-subarray/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_918.java) | |Medium|Array, DP, Monotonic Queue
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|917|[Reverse Only Letters](https://leetcode.com/problems/reverse-only-letters/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_917.java)||Easy|
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|914|[X of a Kind in a Deck of Cards](https://leetcode.com/problems/x-of-a-kind-in-a-deck-of-cards/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_914.java)||Easy|
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|912|[Sort an Array](https://leetcode.com/problems/sort-an-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_912.java)||Easy|
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packagecom.fishercoder.solutions;
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publicclass_918 {
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publicstaticclassSolution1 {
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/**
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* This is my original solution, but results in TLE on LeetCode.
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* Time: O(n^2)
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*/
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publicintmaxSubarraySumCircular(int[]nums) {
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int[]prefixSums;
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intmaxSum =Integer.MIN_VALUE;
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for (inti =0;i <nums.length;i++) {
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prefixSums =newint[nums.length];
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for (intj =i,k =0;j < (i +nums.length);j++) {
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if (k ==0) {
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prefixSums[k] =nums[(j +nums.length) %nums.length];
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}else {
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prefixSums[k] =prefixSums[k -1] +nums[(j +nums.length) %nums.length];
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}
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maxSum =Math.max(maxSum,prefixSums[k++]);
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}
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}
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returnmaxSum;
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}
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}
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publicstaticclassSolution2 {
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/**
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* Credit: https://leetcode.com/problems/maximum-sum-circular-subarray/discuss/178422/One-Pass
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* Think of two cases:
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* 1. the max comes from the contiguous part of the original array
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* 2. the max comes from connecting the tail part and the head part of the original array.
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* See graph from the above link.
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* <p>
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* Time: O(n)
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* <p>
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* This is a follow-up from https://leetcode.com/problems/maximum-subarray/ which is solved by Kadane's algorithm.
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*/
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publicintmaxSubarraySumCircular(int[]nums) {
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intcurrMax =0;
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intglobalMax =nums[0];
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intcurrMin =0;
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intglobalMin =nums[0];
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inttotal =0;
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for (inti =0;i <nums.length;i++) {
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currMax =Math.max(nums[i],currMax +nums[i]);
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globalMax =Math.max(globalMax,currMax);
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currMin =Math.min(currMin +nums[i],nums[i]);
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globalMin =Math.min(currMin,globalMin);
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total +=nums[i];
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}
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returnglobalMax >0 ?Math.max(globalMax,total -globalMin) :globalMax;
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}
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}
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publicstaticclassSolution3 {
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/**
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* Credit: https://leetcode.com/problems/maximum-sum-circular-subarray/discuss/633058/Java-or-C%2B%2B-or-Python3-or-With-detailed-explanation-or-O(N)-time-or-O(1)
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* This one is similar to the above Solution2, but only slightly differs in that it starts from i = 1 instead of i = 0
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* And it listed out a few examples to help illustrate why this algorithm makes sense.
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* Which I think is easier to make sense of.
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* <p>
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* Time: O(n)
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* <p>
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* This is a follow-up from https://leetcode.com/problems/maximum-subarray/ which is solved by Kadane's algorithm.
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*/
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publicintmaxSubarraySumCircular(int[]nums) {
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intcurrMax =nums[0];
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intglobalMax =nums[0];
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intcurrMin =nums[0];
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intglobalMin =nums[0];
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inttotal =nums[0];
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for (inti =1;i <nums.length;i++) {
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currMax =Math.max(nums[i],currMax +nums[i]);
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globalMax =Math.max(globalMax,currMax);
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currMin =Math.min(currMin +nums[i],nums[i]);
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globalMin =Math.min(currMin,globalMin);
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total +=nums[i];
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}
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returnglobalMax >0 ?Math.max(globalMax,total -globalMin) :globalMax;
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}
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}
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}
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packagecom.fishercoder;
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importcom.fishercoder.solutions._918;
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importorg.junit.BeforeClass;
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importorg.junit.Test;
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importstaticorg.junit.Assert.assertEquals;
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publicclass_918Test {
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privatestatic_918.Solution1solution1;
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privatestatic_918.Solution2solution2;
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privatestatic_918.Solution3solution3;
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@BeforeClass
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publicstaticvoidsetup() {
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solution1 =new_918.Solution1();
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solution2 =new_918.Solution2();
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solution3 =new_918.Solution3();
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}
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@Test
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publicvoidtest1() {
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assertEquals(3,solution1.maxSubarraySumCircular(newint[]{1, -2,3, -2}));
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}
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@Test
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publicvoidtest2() {
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assertEquals(10,solution1.maxSubarraySumCircular(newint[]{5, -3,5}));
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}
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@Test
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publicvoidtest3() {
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assertEquals(4,solution1.maxSubarraySumCircular(newint[]{3, -1,2, -1}));
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}
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@Test
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publicvoidtest4() {
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assertEquals(3,solution1.maxSubarraySumCircular(newint[]{3, -2,2, -3}));
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}
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@Test
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publicvoidtest5() {
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assertEquals(-1,solution1.maxSubarraySumCircular(newint[]{-2, -3, -1}));
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}
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@Test
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publicvoidtest6() {
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assertEquals(10,solution1.maxSubarraySumCircular(newint[]{5, -3,5}));
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}
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@Test
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publicvoidtest7() {
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assertEquals(10,solution2.maxSubarraySumCircular(newint[]{5, -3,5}));
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}
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@Test
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publicvoidtest8() {
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assertEquals(10,solution3.maxSubarraySumCircular(newint[]{5, -3,5}));
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}
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}

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