178

Author: illuz

solutions/178.Rank_Scores/AC_order.sql

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+SELECT A.Score Score, 
+(
+    SELECT COUNT(DISTINCT B.Score)
+    FROM Scores B
+    WHERE B.Score >= A.Score
+) Rank
+FROM Scores A
+ORDER BY A.Score DESC
+

solutions/178.Rank_Scores/AC_variables.sql

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+SELECT Score, 
+(
+    CASE
+    # if prev = curRow.Score then return rank
+    WHEN @prev = Score THEN @rank
+    # else let prev = curRow.Score, rank++, and return rank
+    WHEN (@prev := Score) IS NOT NULL THEN @rank := @rank + 1
+    END
+)
+FROM Scores,
+# SELECT to initialize rank, prev. The 'a': Every derived table must have its own alias
+(SELECT @rank := 0, @prev := NULL) a
+ORDER BY Score DESC
+

solutions/178.Rank_Scores/readme.md

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+## 178. Rank Scores (Medium)
+
+### **链接**：
+题目：https://leetcode.com/problems/rank-scores/  
+代码(github)：https://github.com/illuz/leetcode
+
+### **题意**：
+给分数排名。
+
+### **分析**：
+
+1. 把 SELECT 套进去。
+2. 用 CASE 和 变量，逐行处理，速度比 1 变了很多。
+