5 problems solved.

lintcoder · lintcoder · commit 4e67506627a3 · 2021-07-09T22:21:39.000+08:00
diff --git a/src/1903.cpp b/src/1903.cpp
@@ -0,0 +1,29 @@
+string largestOddNumber(string num) {
+        int len = num.size();
+        int index = -1;
+        bool flag = false;
+        for (int i = len-1; i >= 0; --i)
+        {
+            int tmp = num[i]-'0';
+            switch (tmp)
+            {
+                case 1:
+                case 3:
+                case 5:
+                case 7:
+                case 9:
+                    index = i;
+                    flag = true;
+                    break;
+                default:
+                    break;
+            }
+            if (flag)
+                break;
+        }
+        
+        if (index == -1)
+            return "";
+        else
+            return num.substr(0, index+1);
+    }
diff --git a/src/1909.cpp b/src/1909.cpp
@@ -0,0 +1,41 @@
+bool canBeIncreasing(vector<int>& nums) {
+        int len = nums.size();
+        if (len <= 2)
+            return true;
+        
+        int i = 0;
+        for (; i < len-1; ++i)
+        {
+            if (nums[i+1] <= nums[i])
+                break;
+        }
+        if (i >= len-2)
+            return true;
+        int j = i;
+        if (i == 0 || (i > 0 && nums[i+1] > nums[i-1]))
+        {
+            i += 1;
+            for (; i < len-1; ++i)
+            {
+                if (nums[i+1] <= nums[i])
+                    break;
+            }
+            if (i == len-1)
+                return true;
+        }
+        
+        i = j;
+        if (i > 0 && nums[i] < nums[i+2])
+        {
+            i += 2;
+            for (; i < len-1; ++i)
+            {
+                if (nums[i+1] <= nums[i])
+                    break;
+            }
+            if (i == len-1)
+                return true;
+        }
+        
+        return false;
+    }
diff --git a/src/1920.cpp b/src/1920.cpp
@@ -0,0 +1,10 @@
+vector<int> buildArray(vector<int>& nums) {
+        int len = nums.size();
+        vector<int> res(len, 0);
+        for (int i = 0; i < len; ++i)
+        {
+            res[i] = nums[nums[i]];
+        }
+        
+        return res;
+    }
diff --git a/src/398.cpp b/src/398.cpp
@@ -0,0 +1,22 @@
+Solution(vector<int>& nums) {
+        int len = nums.size();
+        for (int i = 0; i < len; ++i)
+        {
+            elems[nums[i]].vals.push_back(i);
+            elems[nums[i]].len++;
+        }
+    }
+    
+    int pick(int target) {
+        int len = elems[target].len;
+        
+        return elems[target].vals[rand()%len];
+    }
+    
+    struct Elem
+    {
+        vector<int> vals;
+        int len;
+        Elem():vals({}), len(0){}
+    };
+    map<int, Elem> elems;
diff --git a/src/921.cpp b/src/921.cpp
@@ -0,0 +1,30 @@
+int minAddToMakeValid(string s) {
+        int len = s.size();
+        if (len <= 1)
+            return len;
+        int i = 0;
+        int left = 0, ct = 0;
+        while (i < len)
+        {
+            if (s[i] == '(')
+            {
+                ++left;
+                ++ct;
+            }
+            else
+            {
+                if (left > 0)
+                {
+                    --left;
+                    --ct;
+                }
+                else
+                {
+                    ++ct;
+                }
+            }
+            ++i;
+        }
+        
+        return ct;
+    }
