2024/9/26 LeetCode Hot100 dp

src/main/java/com/cool/hot100/dp/Num152.java

@@ -0,0 +1,79 @@
+package com.cool.hot100.dp;
+
+import org.junit.Test;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/25/23:23
+ * @Description: 152. 乘积最大子数组
+ * Level 4
+ * DayNumber 4
+ * Hard 2
+ * @Link https://leetcode.cn/problems/maximum-product-subarray/description/?envType=study-plan-v2&envId=top-100-liked
+ */
+public class Num152 {
+
+    public int maxProduct(int[] nums) {
+        int length = nums.length;
+        long[] maxF = new long[length];
+        long[] minF = new long[length];
+        for (int i = 0; i < length; i++) {
+            maxF[i] = nums[i];
+            minF[i] = nums[i];
+        }
+        for (int i = 1; i < length; ++i) {
+            maxF[i] = Math.max(maxF[i - 1] * nums[i], Math.max(nums[i], minF[i - 1] * nums[i]));
+            minF[i] = Math.min(minF[i - 1] * nums[i], Math.min(nums[i], maxF[i - 1] * nums[i]));
+            if (minF[i] < (-1 << 31)) {
+                minF[i] = nums[i];
+            }
+        }
+        int ans = (int) maxF[0];
+        for (int i = 1; i < length; ++i) {
+            ans = Math.max(ans, (int) maxF[i]);
+        }
+        return ans;
+    }
+    public int maxProduct1(int[] nums) {
+        int length=nums.length;
+        int[] maxArr=new int[length];
+        int[] minArr=new int[length];
+        for(int i=0;i<length;i++){
+            minArr[i]=nums[i];
+            maxArr[i]=nums[i];
+        }
+        for(int i=1;i<length;i++){
+            minArr[i]=Math.min(minArr[i-1]*nums[i],Math.min(nums[i],maxArr[i-1]*nums[i]));
+            maxArr[i]=Math.max(maxArr[i-1]*nums[i],Math.max(nums[i],minArr[i-1]*nums[i]));
+        }
+        int res=maxArr[0];
+        for(int i=1;i<length;i++){
+            res=Math.max(res,maxArr[i]);
+        }
+        return res;
+    }
+    /**
+     * @Author Cool
+     * @Date 0:35 2024/9/26
+     * 滚动数组
+     **/
+    public int maxProduct2(int[] nums) {
+        int length=nums.length;
+        int maxArr=nums[0];
+        int minArr=nums[0];
+        int res=nums[0];
+        for(int i=1;i<length;i++){
+            int maxTemp=maxArr,minTemp=minArr;
+            minArr=Math.min(minTemp*nums[i],Math.min(nums[i],maxTemp*nums[i]));
+            maxArr=Math.max(maxTemp*nums[i],Math.max(nums[i],minTemp*nums[i]));
+            res=Math.max(res,maxArr);
+        }
+        return res;
+    }
+    @Test
+    public void test(){
+        maxProduct2(new int[]{2,3,-2,4});
+    }
+}

src/main/java/com/cool/hot100/dp/Num300.java

@@ -12,4 +12,54 @@ package com.cool.hot100.dp;
  * @Link https://leetcode.cn/problems/longest-increasing-subsequence/description/?envType=study-plan-v2&envId=top-100-liked
  */
 public class Num300 {
+    public int lengthOfLIS(int[] nums) {
+        if(nums.length==0){
+            return 0;
+        }
+        int[]dp=new int[nums.length];
+        dp[0]=1;
+        int res=1;
+        for(int i=1;i<nums.length;i++){
+            dp[i]=1;
+            for(int j=0;j<i;j++){
+                if(nums[j]<nums[i]){
+                    dp[i]=Math.max(dp[i],dp[j]+1);
+                }
+            }
+            res=Math.max(res,dp[i]);
+        }
+        return res;
+    }
+    /**
+     * @Author Cool
+     * @Date 23:15 2024/9/25
+     * 贪心+二分解法（看不懂）
+     **/
+    public int lengthOfLIS1(int[] nums) {
+        int len = 1, n = nums.length;
+        if (n == 0) {
+            return 0;
+        }
+        int[] d = new int[n + 1];
+        d[len] = nums[0];
+        for (int i = 1; i < n; ++i) {
+            if (nums[i] > d[len]) {
+                d[++len] = nums[i];
+            } else {
+                int l = 1, r = len, pos = 0; // 如果找不到说明所有的数都比 nums[i] 大，此时要更新 d[1]，所以这里将 pos 设为 0
+                while (l <= r) {
+                    int mid = (l + r) >> 1;
+                    if (d[mid] < nums[i]) {
+                        pos = mid;
+                        l = mid + 1;
+                    } else {
+                        r = mid - 1;
+                    }
+                }
+                d[pos + 1] = nums[i];
+            }
+        }
+        return len;
+    }
+
 }