6 problems solved.

lintcoder · lintcoder · commit f4df8f7cd3c9 · 2021-06-05T21:35:56.000+08:00
diff --git a/src/1784.cpp b/src/1784.cpp
@@ -0,0 +1,15 @@
+bool checkOnesSegment(string s) {
+        int len1 = 0;
+        int len = s.size();
+        if (len == 1)
+            return true;
+        
+        int i = 1;
+        while (i < len && s[i] == '1')
+            ++i;
+        if (i == len)
+            return true;
+        while (i < len && s[i] == '0')
+            ++i;
+        return i == len;
+    }
diff --git a/src/1791.cpp b/src/1791.cpp
@@ -0,0 +1,9 @@
+int findCenter(vector<vector<int>>& edges) {
+        int a = edges[0][0], b = edges[0][1];
+        int c = edges[1][0], d = edges[1][1];
+        
+        if (c == a || c == b)
+            return c;
+        else
+            return d;
+    }
diff --git a/src/1869.cpp b/src/1869.cpp
@@ -0,0 +1,51 @@
+bool checkZeroOnes(string s) {
+        int len1 = 0;
+        int len0 = 0;
+        int maxlen1 = 0, maxlen0 = 0;
+        
+        int len = s.size();
+        int i = 1;
+        
+        if (len == 0)
+            return false;
+        if (s[0] == '1')
+            len1 = 1;
+        else
+            len0 = 1;
+        
+        while (i < len)
+        {
+            if (s[i] == '1')
+            {
+                if (len1 > 0)
+                    ++len1;
+                else
+                {
+                    if (len0 > maxlen0)
+                        maxlen0 = len0;
+                    len0 = 0;
+                    len1 = 1;
+                }
+            }
+            else
+            {
+                if (len0 > 0)
+                    ++len0;
+                else
+                {
+                    if (len1 > maxlen1)
+                        maxlen1 = len1;
+                    len0 = 1;
+                    len1 = 0;
+                }
+            }
+            ++i;
+        }
+        
+        if (len1 > 0 && len1 > maxlen1)
+            maxlen1 = len1;
+        if (len0 > 0 && len0 > maxlen0)
+            maxlen0 = len0;
+    
+        return maxlen1 > maxlen0;
+    }
diff --git a/src/1876.cpp b/src/1876.cpp
@@ -0,0 +1,46 @@
+int countGoodSubstrings(string s) {
+        int len = s.size();
+        if (len < 3)
+            return 0;
+        
+        int ct = 0;
+        int a = s[0], b = s[1];
+        
+        int i = 2;
+        while (i < len)
+        {
+            if (a != b)
+            {
+                if (s[i] != a && s[i] != b)
+                {
+                    a = b;
+                    b = s[i];
+                    ++ct;
+                    ++i;
+                }
+                else if (s[i] == a)
+                {
+                    a = b;
+                    b = s[i];
+                    ++i;
+                }
+                else
+                {
+                    a = b;
+                    if (i+1 >= len)
+                        break;
+                    b = s[i+1];
+                    i += 2;
+                }
+            }
+            else
+            {
+                if (i+1 >= len)
+                    break;
+                b = s[i];
+                ++i;
+            }
+        }
+        
+        return ct;
+    }
diff --git a/src/1877.cpp b/src/1877.cpp
@@ -0,0 +1,15 @@
+int minPairSum(vector<int>& nums) {
+        sort(nums.begin(), nums.end());
+        
+        int len = nums.size();
+        int maxval = 0;
+        int n = len/2;
+        for (int i = 0; i < n; ++i)
+        {
+            int val = nums[i]+nums[len-1-i];
+            if (val > maxval)
+                maxval = val;
+        }
+        
+        return maxval;
+    }
diff --git a/src/1880.cpp b/src/1880.cpp
@@ -0,0 +1,14 @@
+bool isSumEqual(string firstWord, string secondWord, string targetWord) {
+        int len1 = firstWord.size();
+        int len2 = secondWord.size();
+        int len = targetWord.size();
+        int val1 = 0, val2 = 0, val = 0;
+        for (int i = 0; i < len1; ++i)
+            val1 = 10*val1 + firstWord[i]-'a';
+        for (int i = 0; i < len2; ++i)
+            val2 = 10*val2 + secondWord[i]-'a';
+        for (int i = 0; i < len; ++i)
+            val = 10*val + targetWord[i]-'a';
+        
+        return val1 + val2 == val;
+    }
