76. minimum window substring

Author: shariarfaisal

76.minimum-window-substring.go

@@ -0,0 +1,64 @@
+package leetcode
+
+/*
+ * @lc app=leetcode id=76 lang=golang
+ *
+ * [76] Minimum Window Substring
+ */
+
+// @lc code=start
+func minWindow(s string, t string) string {
+
+	// init
+	// 1. init tMap
+	tMap := make(map[byte]int)
+	for i := 0; i < len(t); i++ {
+		tMap[t[i]]++
+	}
+	// 2. init sMap
+	sMap := make(map[byte]int)
+	// 3. init left, right, minLen, minLeft
+	left, right, minLen, minLeft := 0, 0, len(s)+1, 0
+	// 4. init valid
+	valid := 0
+
+	// loop
+	for right < len(s) {
+		// 1. add right
+		c := s[right]
+		right++
+		// 2. update sMap
+		if _, ok := tMap[c]; ok {
+			sMap[c]++
+			if sMap[c] == tMap[c] {
+				valid++
+			}
+		}
+		// 3. shrink left
+		for valid == len(tMap) {
+			// 3.1 update minLen, minLeft
+			if right-left < minLen {
+				minLen = right - left
+				minLeft = left
+			}
+			// 3.2 remove left
+			d := s[left]
+			left++
+			// 3.3 update sMap
+			if _, ok := tMap[d]; ok {
+				if sMap[d] == tMap[d] {
+					valid--
+				}
+				sMap[d]--
+			}
+		}
+	}
+
+	// return
+	if minLen == len(s)+1 {
+		return ""
+	}
+	return s[minLeft : minLeft+minLen]
+}
+
+// @lc code=end