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Aug 31, 2020
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Update _373.java #98

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90 changes: 38 additions & 52 deletions src/main/java/com/fishercoder/solutions/_373.java
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Original file line number Diff line number Diff line change
Expand Up @@ -6,60 +6,46 @@
import java.util.Queue;

public class _373 {
public static class Solution1 {

final int[][] neighbors = new int[][]{{0, 1}, {1, 0}};

public List<int[]> kSmallestPairs(int[] nums1, int[] nums2, int k) {
List<int[]> result = new ArrayList<>();
if (nums1 == null
|| nums2 == null
|| k == 0
|| nums1.length == 0
|| nums2.length == 0) {
return result;
}
Queue<Pair> meanHeap = new PriorityQueue<>();
meanHeap.offer(new Pair(0, 0, nums1[0] + nums2[0]));
boolean[][] visited = new boolean[nums1.length][nums2.length];
visited[0][0] = true;//we start form (0,0), so mark it as visited
while (k > 0 && !meanHeap.isEmpty()) {
Pair pair = meanHeap.poll();
result.add(new int[]{nums1[pair.row], nums2[pair.col]});
k--;
for (int[] neighbor : neighbors) {
int nextRow = pair.row + neighbor[0];
int nextCol = pair.col + neighbor[1];
if (nextRow < 0
|| nextCol < 0
|| nextRow >= nums1.length
|| nextCol >= nums2.length
|| visited[nextRow][nextCol]) {
continue;
}
visited[nextRow][nextCol] = true;
meanHeap.offer(new Pair(nextRow, nextCol, nums1[nextRow] + nums2[nextCol]));
}
}

return result;
}

class Pair implements Comparable<Pair> {
int row;
int col;
int sum;

public Pair(int row, int col, int sum) {
this.row = row;
this.col = col;
this.sum = sum;
}

@Override
public int compareTo(Pair that) {
return this.sum - that.sum;
public class Solution {

int[][] dirs = {{0,1},{1,0},{1,1}};
public List<List<Integer>> kSmallestPairs(int[] nums1, int[] nums2, int k) {

List<List<Integer>> result = new ArrayList<>();

// EDGE CASE
if(nums1==null || nums2==null || nums1.length==0 || nums2.length==0) return result;

// visited array
boolean[][] visited = new boolean[nums1.length][nums2.length];

// Min Heap
PriorityQueue<int[]> pq = new PriorityQueue<>((a,b)->{
return ( a[0]+a[1] ) - ( b[0]+b[1] ) ;
});

int[] temp = new int[]{nums1[0],nums2[0],0,0};
pq.add(temp);
visited[0][0]= true;

while(!pq.isEmpty()){
int[] arr = pq.poll();
List<Integer> ls = new ArrayList<>();
ls.add(arr[0]);ls.add(arr[1]);
result.add(ls);

if(result.size()==k) break;
int i=arr[2],j=arr[3];

for(int[] dir : dirs){
int dx=i+dir[0],dy=j+dir[1];
if(dx<0 || dx>=nums1.length || dy<0 || dy>=nums2.length || visited[dx][dy]) continue;
pq.add(new int[]{nums1[dx],nums2[dy],dx,dy});
visited[dx][dy] = true;
}
}
return result;
}
}
}