feat: solve problem 78

hard/76. Minimum Window Substring.go

@@ -0,0 +1,47 @@
+package hard
+
+import "math"
+
+func minWindow(s string, t string) string {
+	if len(s) == 0 || len(t) == 0 || len(s) < len(t) {
+		return ""
+	}
+
+	mapStr := make([]int, 128)
+	count := len(t)
+	start, end := 0, 0
+	minLen, startIndex := math.MaxInt32, 0
+	for _, val := range t {
+		mapStr[val]++
+	}
+
+	for end < len(s) {
+		if mapStr[s[end]] > 0 {
+			count--
+		}
+		mapStr[s[end]]--
+		end++
+
+		for count == 0 {
+			if end-start < minLen {
+				minLen = end - start + 1
+				startIndex = start
+			}
+
+			if mapStr[s[start]] == 0 {
+				count++
+			}
+			mapStr[s[start]]++
+			start++
+		}
+	}
+
+	if minLen == math.MaxInt32 {
+		return ""
+	}
+
+	return s[startIndex : startIndex+minLen-1]
+}
+
+//Time: 0(N)
+//Space: O(1)