add new solutions

solutions/29/q2977/solution.go

@@ -0,0 +1,96 @@
+package q2977
+
+import "math"
+
+const INF int = math.MaxInt
+
+func minimumCost(source string, target string, original []string, changed []string, cost []int) int64 {
+	// Index words
+	words := make([]string, 0, len(original)+len(changed))
+	wIdx := make(map[string]int, len(original)+len(changed))
+
+	addWords := func(arr []string) {
+		for _, word := range arr {
+			if _, ok := wIdx[word]; !ok {
+				words = append(words, word)
+				wIdx[word] = len(words) - 1
+			}
+		}
+	}
+	addWords(original)
+	addWords(changed)
+
+	// Calculate min cost from `original` to `changed`
+	mat := make([][]int, len(words))
+	for i := range mat {
+		mat[i] = make([]int, len(words))
+		mat[0][i] = INF
+	}
+	for i := 1; i < len(words); i++ {
+		copy(mat[i], mat[0])
+	}
+
+	q := make([][3]int, 0, 2*len(original)) // src, dst, cost
+	for i := range original {
+		src, dst, cst := wIdx[original[i]], wIdx[changed[i]], cost[i]
+		q = append(q, [3]int{src, dst, cst})
+		mat[src][dst] = min(mat[src][dst], cst)
+	}
+
+	for ; len(q) > 0; q = q[1:] {
+		src, dst, cst := q[0][0], q[0][1], q[0][2]
+		for next := range mat {
+			if next == src || mat[dst][next] == INF {
+				continue
+			}
+			nextCost := mat[dst][next] + cst
+			if nextCost < mat[src][next] {
+				mat[src][next] = nextCost
+				q = append(q, [3]int{src, next, nextCost})
+			}
+		}
+	}
+
+	// Calculate min cost for converting entire string
+	lengthsT := make(map[int]struct{}, len(original))
+	for i := range original {
+		lengthsT[len(original[i])] = struct{}{}
+	}
+	lengths := make([]int, 0, len(lengthsT))
+	for l := range lengthsT {
+		lengths = append(lengths, l)
+	}
+
+	minCost := make([]int, len(source)+1)
+	for i := range minCost {
+		minCost[i] = INF
+	}
+	minCost[0] = 0
+
+	for i := 1; i < len(minCost); i++ {
+		if source[i-1] == target[i-1] {
+			minCost[i] = minCost[i-1]
+		}
+		for _, l := range lengths {
+			if l > i || minCost[i-l] == INF {
+				continue
+			}
+			srcStr, dstStr := source[i-l:i], target[i-l:i]
+			src, ok1 := wIdx[srcStr]
+			dst, ok2 := wIdx[dstStr]
+			if !ok1 || !ok2 || mat[src][dst] == INF {
+				continue
+			}
+
+			minCost[i] = min(minCost[i], minCost[i-l]+mat[src][dst])
+		}
+	}
+
+	ret := minCost[len(minCost)-1]
+	if ret == INF {
+		return -1
+	}
+	return int64(ret)
+}
+
+var _ = minimumCost