Merge branch 'youngyangyang04:master' into master

problems/0055.跳跃游戏.md

@@ -122,6 +122,24 @@ class Solution:
 ```
 
 Go：
+```Go
+func canJUmp(nums []int) bool {
+	if len(nums)<=1{
+		return true
+	}
+	dp:=make([]bool,len(nums))
+	dp[0]=true
+	for i:=1;i<len(nums);i++{
+		for j:=i-1;j>=0;j--{
+			if dp[j]&&nums[j]+j>=i{
+				dp[i]=true
+				break
+			}
+		}
+	}
+	return dp[len(nums)-1]
+}
+```
 
 
 

problems/0383.赎金信.md

@@ -136,7 +136,34 @@ class Solution {
 ```
 
 Python：
+```
+class Solution(object):
+    def canConstruct(self, ransomNote, magazine):
+        """
+        :type ransomNote: str
+        :type magazine: str
+        :rtype: bool
+        """
         
+        # use a dict to store the number of letter occurance in ransomNote
+        hashmap = dict()
+        for s in ransomNote:
+            if s in hashmap:
+                hashmap[s] += 1
+            else:
+                hashmap[s] = 1
+        
+        # check if the letter we need can be found in magazine
+        for l in magazine:
+            if l in hashmap:
+                hashmap[l] -= 1
+        
+        for key in hashmap:
+            if hashmap[key] > 0:
+                return False
+        
+        return True
+```
 
 Go：
 

problems/0454.四数相加II.md

@@ -121,6 +121,37 @@ class Solution {
 
 Python：
 
+```
+class Solution(object):
+    def fourSumCount(self, nums1, nums2, nums3, nums4):
+        """
+        :type nums1: List[int]
+        :type nums2: List[int]
+        :type nums3: List[int]
+        :type nums4: List[int]
+        :rtype: int
+        """
+        # use a dict to store the elements in nums1 and nums2 and their sum
+        hashmap = dict()
+        for n1 in nums1:
+            for n2 in nums2:
+                if n1 + n2 in hashmap:
+                    hashmap[n1+n2] += 1
+                else:
+                    hashmap[n1+n2] = 1
+        
+        # if the -(a+b) exists in nums3 and nums4, we shall add the count
+        count = 0
+        for n3 in nums3:
+            for n4 in nums4:
+                key = - n3 - n4
+                if key in hashmap:
+                    count += hashmap[key]
+        return count
+                
+
+```
+
 
 Go：
 

problems/0516.最长回文子序列.md

@@ -175,36 +175,35 @@ Python：
 Go：
 ```Go
 func longestPalindromeSubseq(s string) int {
-    str:=[]byte(s)
+	lenth:=len(s)
-    dp:=make([][]int,len(s))
+	dp:=make([][]int,lenth)
-    for i:=0;i<len(s);i++{
+	for i:=0;i<lenth;i++{
-        dp[i]=make([]int,len(s))
+		for j:=0;j<lenth;j++{
+			if dp[i]==nil{
+				dp[i]=make([]int,lenth)
 			}
-    for i:=1;i<len(s);i++{
+			if i==j{
-        for j:=i-1;j>=0;j--{
+				dp[i][j]=1
-            if str[i]==str[j]{
+			}
-                if j==i-1{
+		}
-                    dp[j][i]=2
+	}
+	for i:=lenth-1;i>=0;i--{
+		for j:=i+1;j<lenth;j++{
+			if s[i]==s[j]{
+				dp[i][j]=dp[i+1][j-1]+2
 			}else {
-                    dp[j][i]=dp[j+1][i-1]+2
+				dp[i][j]=max(dp[i+1][j],dp[i][j-1])
-                }
-            }else{
-                dp[j][i]=Max(dp[j+1][i],dp[j][i-1])
 			}
 		}
 	}
-    return dp[0][len(s)-1]
+
-}
+	return dp[0][lenth-1]
-func Max(a,b int)int{
-    if a>b{
-        return a
-    }
-    return b
 }
 ```
 
 
 
+
 -----------------------
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