| # | Title | Solutions | Video | Difficulty | Tag

|-----|----------------|---------------|--------|-------------|-------------

|1640|[Check Array Formation Through Concatenation](https://leetcode.com/problems/check-array-formation-through-concatenation/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1640.java)||Easy|Array, Sort|

|1637|[Widest Vertical Area Between Two Points Containing No Points](https://leetcode.com/problems/widest-vertical-area-between-two-points-containing-no-points/)|[Javascript](./javascript/_1637.js)|| Medium| Sort|

|1636|[Sort Array by Increasing Frequency](https://leetcode.com/problems/sort-array-by-increasing-frequency/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1636.java)||Easy|Array, Sort|

|1630|[Arithmetic Subarrays](https://leetcode.com/problems/arithmetic-subarrays/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1630.java)||Medium|Sort|

packagecom.fishercoder.solutions;

publicclass_1640 {

publicstaticclassSolution1 {

publicbooleancanFormArray(int[]arr,int[][]pieces) {

for (int[]piece :pieces) {

intfirst =piece[0];

intindex =findIndex(arr,first);

if (index == -1) {

returnfalse;

}

inti =0;

for (intj =index;i <piece.length &&j <arr.length;i++,j++) {

if (arr[j] !=piece[i]) {

returnfalse;

}

}

if (i !=piece.length) {

returnfalse;

}

}

returntrue;

}

privateintfindIndex(int[]arr,intkey) {

for (inti =0;i <arr.length;i++) {

if (arr[i] ==key) {

returni;

}

}

return -1;

}

}

}

packagecom.fishercoder;

importcom.fishercoder.solutions._1640;

importorg.junit.BeforeClass;

importorg.junit.Test;

importstaticorg.junit.Assert.assertEquals;

publicclass_1640Test {

privatestatic_1640.Solution1solution1;

privatestaticint[]arr;

privatestaticint[][]pieces;

publicstaticvoidsetup() {

solution1 =new_1640.Solution1();

}

publicvoidtest1() {

arr =newint[]{85};

pieces =newint[][]{{85}};

assertEquals(true,solution1.canFormArray(arr,pieces));

}

publicvoidtest2() {

arr =newint[]{91,4,64,78};

pieces =newint[][]{{78}, {4,64}, {91}};

assertEquals(true,solution1.canFormArray(arr,pieces));

}

publicvoidtest3() {

arr =newint[]{49,18,16};

pieces =newint[][]{{16,18,49}};

assertEquals(false,solution1.canFormArray(arr,pieces));

}

}