5 problems solved.

lintcoder · lintcoder · commit 12ef63e70bad · 2020-01-19T20:19:23.000+08:00
diff --git a/src/1299.cpp b/src/1299.cpp
@@ -0,0 +1,20 @@
+vector<int> replaceElements(vector<int>& arr) {
+        int len = arr.size();
+        if (len == 1)
+            return {-1};
+        
+        vector<int> res(len, -1);
+        int maxnum = -1;
+        int i = len-1;
+        while (i > 0)
+        {
+            if (arr[i] > maxnum)
+            {
+                maxnum = arr[i];
+            }
+            res[i-1] = maxnum;
+            --i;
+        }
+        
+        return res;
+    }
diff --git a/src/1313.cpp b/src/1313.cpp
@@ -0,0 +1,16 @@
+vector<int> decompressRLElist(vector<int>& nums) {
+        int len = nums.size();
+        int total = 0;
+        for (int i = 0; i < len; i += 2)
+            total += nums[i];
+        vector<int> res(total, 0);
+        int k = 0;
+        for (int i = 0; i < len; i += 2)
+        {
+            int lim = k+nums[i];
+            for (; k < lim; ++k)
+                res[k] = nums[i+1];
+        }
+        
+        return res;
+    }
diff --git a/src/1323.cpp b/src/1323.cpp
@@ -0,0 +1,16 @@
+int maximum69Number (int num) {
+        string s = to_string(num);
+        int res = 0;
+        int len = s.size();
+        for (int i = 0; i < len; ++i)
+            if (s[i] == '6')
+            {
+                s[i] = '9';
+                break;
+            }
+        
+        for (int i = 0; i < len; ++i)
+            res = res*10 + (s[i]-'0');
+        
+        return res;
+    }
diff --git a/src/581.cpp b/src/581.cpp
@@ -0,0 +1,19 @@
+int findUnsortedSubarray(vector<int>& nums) {
+        int len = nums.size();
+        if (len <= 1)
+            return 0;
+        
+        vector<int> vec(nums);
+        sort(vec.begin(), vec.end());
+        int i = 0;
+        for (i = 0; i < len; ++i)
+            if (nums[i] != vec[i])
+                break;
+        if (i == len)
+            return 0;
+        int j = len-1;
+        for (j = len-1; j >= 0; --j)
+            if (nums[j] != vec[j])
+                break;
+        return j-i+1;
+    }
diff --git a/src/98.cpp b/src/98.cpp
@@ -0,0 +1,27 @@
+bool isValidBST(TreeNode* root) {
+        if (root == NULL)
+            return true;
+        list<TreeNode*> lst;
+        midtravel(root, lst);
+        auto lim = lst.end();
+        --lim;
+        for (auto iter = lst.begin(); iter != lim; ++iter)
+        {
+            auto tmp = iter;
+            tmp++;
+            if ((*iter)->val >= (*tmp)->val)
+                return false;
+        }
+        
+        return true;
+    }
+    
+    void midtravel(TreeNode* node, list<TreeNode*>& lst)
+    {
+        if (node != NULL)
+        {
+            midtravel(node->left, lst);
+            lst.push_back(node);
+            midtravel(node->right, lst);
+        }
+    }
