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Commit6cc532c

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add 1439
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‎README.md

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@@ -269,6 +269,7 @@ _If you like this project, please leave me a star._ ★
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|1447|[Simplified Fractions](https://leetcode.com/problems/simplified-fractions/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1447.java)||Medium|Math|
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|1446|[Consecutive Characters](https://leetcode.com/problems/consecutive-characters/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1446.java)||Easy|String|
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|1441|[Build an Array With Stack Operations](https://leetcode.com/problems/build-an-array-with-stack-operations/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1441.java)||Easy|Stack|
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|1439|[Find the Kth Smallest Sum of a Matrix With Sorted Rows](https://leetcode.com/problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1439.java)||Hard|Array, Binary Search, PriorityQueue, Matrix|
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|1437|[Check If All 1's Are at Least Length K Places Away](https://leetcode.com/problems/check-if-all-1s-are-at-least-length-k-places-away/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1437.java)||Medium|Array|
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|1436|[Destination City](https://leetcode.com/problems/destination-city/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1436.java)||Easy|String|
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|1432|[Max Difference You Can Get From Changing an Integer](https://leetcode.com/problems/max-difference-you-can-get-from-changing-an-integer/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1432.java)||Medium|String|
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packagecom.fishercoder.solutions;
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importjava.util.Arrays;
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importjava.util.Comparator;
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importjava.util.TreeSet;
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publicclass_1439 {
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publicstaticclassSolution1 {
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/**
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* My completely own implementation after reading the hint on LeetCode:
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* 1. We put the sum along with every single element's index in each row as an array into a TreeSet, let it sort by its sum ascendingly;
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* each time we poll an element out of the set, we can find the next m smallest sums by moving each row index to the right by one.
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* 2. priority queue doesn't help in this case unless used in combination with a set to filter out duplicates;
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* 3. implement a customized comparator for treeset: if sum i.e. entry[0] doesn't equal, then it's not a duplicate,
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* then we compare the rest of the elements in the array, as long as anyone of them differs at the same index, it's not a duplicate.
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*/
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publicintkthSmallest(int[][]mat,intk) {
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TreeSet<int[]>treeSet =newTreeSet<>(newComparator<int[]>() {
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@Override
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publicintcompare(int[]o1,int[]o2) {
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if (o1[0] !=o2[0]) {
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returno1[0] -o2[0];
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}else {
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for (inti =1;i <o1.length;i++) {
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if (o1[i] !=o2[i]) {
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returno1[i] -o2[i];
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}
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}
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return0;
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}
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}
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});
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intm =mat.length;
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intn =mat[0].length;
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intsum =0;
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int[]entry =newint[m +1];
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for (inti =0;i <m;i++) {
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sum +=mat[i][0];
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}
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entry[0] =sum;
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treeSet.add(entry);
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intcount =0;
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while (count <k) {
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int[]curr =treeSet.pollFirst();
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count++;
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if (count ==k) {
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returncurr[0];
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}
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for (inti =0;i <m;i++) {
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int[]next =Arrays.copyOf(curr,curr.length);
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if (curr[i +1] +1 <n) {
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next[0] -=mat[i][curr[i +1]];
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next[0] +=mat[i][curr[i +1] +1];
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next[i +1]++;
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treeSet.add(next);
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}
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}
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}
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return -1;
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}
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}
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}
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packagecom.fishercoder;
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importcom.fishercoder.common.utils.CommonUtils;
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importcom.fishercoder.solutions._1439;
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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_1439Test {
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privatestatic_1439.Solution1solution1;
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privatestaticint[][]mat;
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privatestaticintexpected;
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privatestaticintk;
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@BeforeClass
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publicstaticvoidsetup() {
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solution1 =new_1439.Solution1();
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}
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@Test
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publicvoidtest1() {
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mat =CommonUtils.convertLeetCodeIrregularLengths2DArrayInputIntoJavaArray("[1,3,11],[2,4,6]");
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expected =7;
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k =5;
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assertEquals(expected,solution1.kthSmallest(mat,k));
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}
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@Test
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publicvoidtest2() {
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mat =CommonUtils.convertLeetCodeIrregularLengths2DArrayInputIntoJavaArray("[1,3,11],[2,4,6]");
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expected =17;
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k =9;
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assertEquals(expected,solution1.kthSmallest(mat,k));
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}
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@Test
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publicvoidtest3() {
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mat =CommonUtils.convertLeetCodeIrregularLengths2DArrayInputIntoJavaArray("[1,10,10],[1,4,5],[2,3,6]");
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expected =9;
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k =7;
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assertEquals(expected,solution1.kthSmallest(mat,k));
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}
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@Test
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publicvoidtest4() {
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mat =CommonUtils.convertLeetCodeIrregularLengths2DArrayInputIntoJavaArray("[1,1,10],[2,2,9]");
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expected =12;
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k =7;
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assertEquals(expected,solution1.kthSmallest(mat,k));
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}
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}

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