DP

h2pl · h2pl · commit 0f184d9f10bc · 2018-04-09T16:49:10.000+08:00
分割整数以及
股票交易两类题型
日不会做
diff --git a/src/DP/其他问题如股票/买入和售出股票最大的收益.java b/src/DP/其他问题如股票/买入和售出股票最大的收益.java
@@ -0,0 +1,7 @@
+package DP.其他问题如股票;
+
+/**
+ * Created by 周杰伦 on 2018/4/9.
+ */
+public class 买入和售出股票最大的收益 {
+}
diff --git a/src/DP/分割整数/分割整数的最大乘积自写.java b/src/DP/分割整数/分割整数的最大乘积自写.java
@@ -0,0 +1,25 @@
+package DP.分割整数;
+
+/**
+ * Created by 周杰伦 on 2018/4/9.
+ */
+public class 分割整数的最大乘积自写 {
+    // 2 = 1+1 3 = 1+2 4=2+2 5=2+3 6=3+3
+    public static void main(String[] args) {
+        System.out.println(integerBreak(10));
+    }
+    public static int integerBreak(int n) {
+        if (n == 1 || n == 0)return 0;
+        int []dp = new int[n + 1];
+        dp[0] = 0;
+        dp[1] = 1;
+        dp[2] = 1;
+        for (int i = 3;i <= n;i ++) {
+            for (int j = 1;j < i;j ++ ) {
+                dp[i] = Math.max(dp[i],dp[j] * (i - j));
+                if ((i-j) * j > dp[i] ) dp[i] = (i - j) * j;
+            }
+        }
+        return dp[n];
+    }
+}
diff --git a/src/DP/分割整数/按平方数来分割整数自写.java b/src/DP/分割整数/按平方数来分割整数自写.java
@@ -0,0 +1,34 @@
+package DP.分割整数;
+
+/**
+ * Created by 周杰伦 on 2018/4/9.
+ */
+public class 按平方数来分割整数自写 {
+    public static void main(String[] args) {
+        System.out.println(numSquares(12));
+    }
+    public static int numSquares(int n) {
+        int []dp = new int[n + 1];
+        dp[1] = 1;
+        for (int i = 2;i <= n;i ++) {
+            //默认等于前一位+1
+            dp[i] = dp[i - 1] + 1;
+            if (isSquare(i)) {
+                dp[i] = 1;
+                continue;
+            }
+            //当差为平方数时直接 等于其+1即可。这样的时间复杂度大大降低。
+            //为onlogn.否则是on2不符合要求
+            for (int j = 1;j * j < i;j ++) {
+                dp[i] = Math.min(dp[i], dp[i - j * j] + 1);
+            }
+        }
+        return dp[n];
+    }
+    public static boolean isSquare(int n) {
+        if (Math.ceil(Math.pow(n,0.5)) == Math.pow(n,0.5)) {
+            return true;
+        }
+        return false;
+    }
+}
