feat: add solutions to lc problems: No.2902

solution/2900-2999/2902.Count of Sub-Multisets With Bounded Sum/Solution.go

@@ -0,0 +1,31 @@
+func countSubMultisets(nums []int, l int, r int) int {
+	multiset := make(map[int]int)
+	for _, num := range nums {
+		multiset[num]++
+	}
+	mem := make([]int, r+1)
+	mem[0] = 1
+	prefix := make([]int, len(mem))
+	for num, occ := range multiset {
+		copy(prefix, mem)
+		for sum := num; sum <= r; sum++ {
+			prefix[sum] = (prefix[sum] + prefix[sum-num]) % mod
+		}
+		for sum := r; sum >= 0; sum-- {
+			if num > 0 {
+				mem[sum] = prefix[sum]
+				if sum >= num*(occ+1) {
+					mem[sum] = (mem[sum] - prefix[sum-num*(occ+1)] + mod) % mod
+				}
+			} else {
+				mem[sum] = (mem[sum] * (occ + 1)) % mod
+			}
+		}
+	}
+	var result int
+	for sum := l; sum <= r; sum++ {
+		result = (result + mem[sum]) % mod
+	}
+	return result
+}
+var mod int = 1e9 + 7