From e92b5b6c0432fb16a2d1aed0ef6f12777f41755c Mon Sep 17 00:00:00 2001
From: YDZ <ydz627@gmail.com>
Date: Fri, 14 Jun 2019 14:21:16 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20problem=2076?=
MIME-Version: 1.0
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---
 .../76. Minimum Window Substring.go           | 40 ++++++++++++++
 .../76. Minimum Window Substring_test.go      | 53 +++++++++++++++++++
 .../0076. Minimum Window Substring/README.md  | 29 ++++++++++
 3 files changed, 122 insertions(+)
 create mode 100644 Algorithms/0076. Minimum Window Substring/76. Minimum Window Substring.go
 create mode 100644 Algorithms/0076. Minimum Window Substring/76. Minimum Window Substring_test.go
 create mode 100644 Algorithms/0076. Minimum Window Substring/README.md

diff --git a/Algorithms/0076. Minimum Window Substring/76. Minimum Window Substring.go b/Algorithms/0076. Minimum Window Substring/76. Minimum Window Substring.go
new file mode 100644
index 00000000..ece9380c
--- /dev/null
+++ b/Algorithms/0076. Minimum Window Substring/76. Minimum Window Substring.go	
@@ -0,0 +1,40 @@
+package leetcode
+
+func minWindow(s string, t string) string {
+	if s == "" || t == "" {
+		return ""
+	}
+	var tFreq, sFreq [256]int
+	result, left, right, finalLeft, finalRight, minW, count := "", 0, -1, -1, -1, len(s)+1, 0
+
+	for i := 0; i < len(t); i++ {
+		tFreq[t[i]-'a']++
+	}
+
+	for left < len(s) {
+		if right+1 < len(s) && count < len(t) {
+			sFreq[s[right+1]-'a']++
+			if sFreq[s[right+1]-'a'] <= tFreq[s[right+1]-'a'] {
+				count++
+			}
+			right++
+		} else {
+			if right-left+1 < minW && count == len(t) {
+				minW = right - left + 1
+				finalLeft = left
+				finalRight = right
+			}
+			if sFreq[s[left]-'a'] == tFreq[s[left]-'a'] {
+				count--
+			}
+			sFreq[s[left]-'a']--
+			left++
+		}
+	}
+	if finalLeft != -1 {
+		for i := finalLeft; i < finalRight+1; i++ {
+			result += string(s[i])
+		}
+	}
+	return result
+}
diff --git a/Algorithms/0076. Minimum Window Substring/76. Minimum Window Substring_test.go b/Algorithms/0076. Minimum Window Substring/76. Minimum Window Substring_test.go
new file mode 100644
index 00000000..73338f49
--- /dev/null
+++ b/Algorithms/0076. Minimum Window Substring/76. Minimum Window Substring_test.go	
@@ -0,0 +1,53 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question76 struct {
+	para76
+	ans76
+}
+
+// para 是参数
+// one 代表第一个参数
+type para76 struct {
+	s string
+	p string
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans76 struct {
+	one string
+}
+
+func Test_Problem76(t *testing.T) {
+
+	qs := []question76{
+
+		question76{
+			para76{"ADOBECODEBANC", "ABC"},
+			ans76{"BANC"},
+		},
+
+		question76{
+			para76{"a", "aa"},
+			ans76{""},
+		},
+
+		question76{
+			para76{"a", "a"},
+			ans76{"a"},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 76------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans76, q.para76
+		fmt.Printf("【input】:%v       【output】:%v\n\n\n", p, minWindow(p.s, p.p))
+	}
+	fmt.Printf("\n\n\n")
+}
diff --git a/Algorithms/0076. Minimum Window Substring/README.md b/Algorithms/0076. Minimum Window Substring/README.md
new file mode 100644
index 00000000..08f10e78
--- /dev/null
+++ b/Algorithms/0076. Minimum Window Substring/README.md	
@@ -0,0 +1,29 @@
+# [76. Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring/)
+
+## 题目
+
+Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).
+
+Example:
+
+```c
+Input: S = "ADOBECODEBANC", T = "ABC"
+Output: "BANC"
+```
+
+Note:    
+
+- If there is no such window in S that covers all characters in T, return the empty string "".
+- If there is such window, you are guaranteed that there will always be only one unique minimum window in S.
+
+## 题目大意
+
+给定一个源字符串 s，再给一个字符串 T，要求在源字符串中找到一个窗口，这个窗口包含由字符串各种排列组合组成的，窗口中可以包含 T 中没有的字符，如果存在多个，在结果中输出最小的窗口，如果找不到这样的窗口，输出空字符串。
+
+## 解题思路
+
+这一题是滑动窗口的题目，在窗口滑动的过程中不断的包含字符串 T，直到完全包含字符串 T 的字符以后，记下左右窗口的位置和窗口大小。每次都不断更新这个符合条件的窗口和窗口大小的最小值。最后输出结果即可。
+
+
+
+