375 finish

Author: aQua

Algorithms/0375.guess-number-higher-or-lower-ii/guess-number-higher-or-lower-ii.go

@@ -1,24 +1,28 @@
 package Problem0375
 
 func getMoneyAmount(n int) int {
-
 	// dp[i][j] 保证能猜出 i<=x<=j 中 x 的具体值的最小金额
 	// dp[1][n] 是答案
-	dp := make([]int, n+1)
-
-	MIN := 1<<63 - 1
+	dp := make([][]int, n+1)
+	for i := range dp {
+		dp[i] = make([]int, n+1)
+	}
 
 	var i, j, k int
 	for j = 2; j <= n; j++ {
-		for i = 1; i < j; i++ {
-			dp[j] = MIN
-			for k = 1; k < i; k++ {
-				dp[j] = min(dp[j], k+max(dp[k-1], k+dp[i-k]))
+		for i = j - 1; 0 < i; i-- {
+			// 为了确保可以猜出 i<=x<=j 中的 x
+			// 第一次，我们可以猜 x 为，i，i+1，...,j-1
+			// 所有这些可能性中的最小值就是 dp[i][j] 的值
+			dp[i][j] = i + dp[i+1][j]
+			for k = i + 1; k < j; k++ {
+				// k+max(dp[i][k-1], dp[k+1][j])) 猜 x 为 k 所花费的最小费用
+				dp[i][j] = min(dp[i][j], k+max(dp[i][k-1], dp[k+1][j]))
 			}
 		}
 	}
 
-	return dp[n]
+	return dp[1][n]
 }
 
 func max(a, b int) int {

Algorithms/0375.guess-number-higher-or-lower-ii/guess-number-higher-or-lower-ii_test.go

@@ -13,7 +13,8 @@ var tcs = []struct {
 	ans int
 }{
 
-	{20, 49},
+	{12, 21},
+	{5, 6},
 	{1, 0},
 	{2, 1},
 	{3, 2},
@@ -24,6 +25,7 @@ var tcs = []struct {
 	{9, 14},
 	{10, 16},
 	{12, 21},
+	{20, 49},
 	{100, 400},
 	{300, 1640},