add: leetcode 0846 readme

leetcode/0846.Hand-of-Straights/README.md

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+# [846. Hand of Straights](https://leetcode-cn.com/problems/hand-of-straights/)
+
+## 题目
+
+Alice has some number of cards and she wants to rearrange the cards into groups so that each group is of size groupSize, and consists of groupSize consecutive cards.
+
+Given an integer array hand where hand[i] is the value written on the ith card and an integer groupSize, return true if she can rearrange the cards, or false otherwise.
+
+**Example 1**:
+
+    Input: hand = [1,2,3,6,2,3,4,7,8], groupSize = 3
+    Output: true
+    Explanation: Alice's hand can be rearranged as [1,2,3],[2,3,4],[6,7,8]
+
+**Example 2**:
+
+    Input: hand = [1,2,3,4,5], groupSize = 4
+    Output: false
+    Explanation: Alice's hand can not be rearranged into groups of 4.
+
+**Constraints:**
+
+- 1 <= hand.length <= 10000
+- 0 <= hand[i] <= 1000000000
+- 1 <= groupSize <= hand.length
+
+## 题目大意
+
+Alice 手中有一把牌，她想要重新排列这些牌，分成若干组，使每一组的牌数都是 groupSize ，并且由 groupSize 张连续的牌组成。
+
+给你一个整数数组 hand 其中 hand[i] 是写在第 i 张牌，和一个整数 groupSize 。如果她可能重新排列这些牌，返回 true ；否则，返回 false 。
+
+## 解题思路
+
+贪心算法
+
+- 对hand升序排序
+- 对hand内数字进行哈希计数（key:数字，value:数量）
+- 遍历hand中的数字，以数量大于1的数字作为顺子开头，寻找顺子后续元素，若无法找到完整顺子则返回false
+- 所有数字都能找到完整顺子返回true
+
+##代码
+
+```go
+package leetcode
+
+import "sort"
+
+func isNStraightHand(hand []int, groupSize int) bool {
+	mp := make(map[int]int)
+	for _, v := range hand {
+		mp[v] += 1
+	}
+	sort.Ints(hand)
+	for _, num := range hand {
+		if mp[num] == 0 {
+			continue
+		}
+		for diff := 0; diff < groupSize; diff++ {
+			if mp[num+diff] == 0 {
+				return false
+			}
+			mp[num+diff] -= 1
+		}
+	}
+	return true
+}
+```