add: my solution for kpairswithlargestsums

Pattern14 - K-way merge/K_Pairs_with_Largest_Sums/solution.go

@@ -0,0 +1,52 @@
+package kpairswithlargestsums
+
+import "container/heap"
+
+/*
+* K Pairs with Largest Sums
+Given two sorted arrays in descending order, find ‘K’ pairs with the largest sum where each pair consists of numbers from both the arrays.
+
+Input: L1=[9, 8, 2], L2=[6, 3, 1], K=3
+Output: [9, 3], [9, 6], [8, 6]
+Explanation: These 3 pairs have the largest sum. No other pair has a sum larger than any of these.
+
+Input: L1=[5, 2, 1], L2=[2, -1], K=3
+Output: [5, 2], [5, -1], [2, 2]
+
+ref: https://leetcode-cn.com/problems/find-k-pairs-with-smallest-sums/
+*/
+
+func kLargestPairs(nums1, nums2 []int, k int) [][]int {
+	var (
+		mheap MinHeap
+	)
+	heap.Init(&mheap)
+	for _, v1 := range nums1 {
+		for _, v2 := range nums2 {
+			if mheap.Len() < k {
+				heap.Push(&mheap, []int{v1, v2})
+			} else if v1+v2 > mheap[0][0]+mheap[0][1] {
+				heap.Pop(&mheap)
+				heap.Push(&mheap, []int{v1, v2})
+			} else {
+				break
+			}
+		}
+	}
+
+	return mheap
+}
+
+type MinHeap [][]int
+
+func (h MinHeap) Len() int            { return len(h) }
+func (h MinHeap) Less(i, j int) bool  { return (h[i][0] + h[i][1]) < (h[j][0] + h[j][1]) }
+func (h MinHeap) Swap(i, j int)       { h[i], h[j] = h[j], h[i] }
+func (h *MinHeap) Push(x interface{}) { *h = append(*h, x.([]int)) }
+func (h *MinHeap) Pop() interface{} {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[:n-1]
+	return x
+}

Pattern14 - K-way merge/K_Pairs_with_Largest_Sums/solution_test.go

@@ -0,0 +1,28 @@
+package kpairswithlargestsums
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_kLargestPairs(t *testing.T) {
+	type args struct {
+		nums1 []int
+		nums2 []int
+		k     int
+	}
+	tests := []struct {
+		name string
+		args args
+		want [][]int
+	}{
+		{"case1", args{[]int{9, 8, 2}, []int{6, 3, 1}, 3}, [][]int{{9, 3}, {9, 6}, {8, 6}}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := kLargestPairs(tt.args.nums1, tt.args.nums2, tt.args.k); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("kLargestPairs() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}