3 problems solved.

lintcoder · lintcoder · commit 59f2caf1803f · 2018-12-08T15:57:05.000+08:00
diff --git a/src/704.cpp b/src/704.cpp
@@ -0,0 +1,19 @@
+int search(vector<int>& nums, int target) {
+        int len = nums.size();
+        int i = 0, j = len-1;
+        while (i < j)
+        {
+            int mid = (i+j)/2;
+            if (nums[mid] == target)
+                return mid;
+            else if (nums[mid] < target)
+                i = mid+1;
+            else
+                j = mid-1;
+        }
+        
+        if (nums[i] == target)
+            return i;
+        else
+            return -1;
+    }
diff --git a/src/724.cpp b/src/724.cpp
@@ -0,0 +1,32 @@
+int pivotIndex(vector<int>& nums) {
+        int len = nums.size();
+        if (len <= 1)
+            return len-1;
+        if (len == 2)
+        {
+            if (nums[1] == 0)
+                return 0;
+            else if (nums[0] == 0)
+                return 1;
+            else
+                return -1;
+        }
+
+        vector<int> subsum(len, 0);
+        int sum = 0;
+        for (int i = 0; i < len; ++i)
+        {
+            sum += nums[i];
+            subsum[i] = sum;
+        }
+        
+        if (sum-nums[0] == 0)
+            return 0;
+        for (int i = 0; i < len-1; ++i)
+        {
+            if (subsum[i] == sum-subsum[i+1])
+            return i+1;
+        }
+
+        return -1;
+    }
diff --git a/src/859.cpp b/src/859.cpp
@@ -0,0 +1,46 @@
+bool buddyStrings(string A, string B) {
+        int len1 = A.size();
+        int len2 = B.size();
+        if (len1 != len2)
+            return false;
+        if (len1 < 2)
+            return false;
+        if (A == B)
+        {
+            array<int, 26> arr = {0};
+            if (len1 > 26)
+                return true;
+            for (int i = 0; i < len1; ++i)
+            {
+                arr[A[i]-'a']++;
+                if (arr[A[i]-'a'] > 1)
+                    return true;
+            }
+            return false;
+        }
+        char a, b;
+        int ct = 0;
+        for (int i = 0; i < len1; ++i)
+        {
+            if (A[i] != B[i])
+            {
+                if (ct == 0)
+                {
+                    a = A[i];
+                    b = B[i];
+                    ++ct; 
+                }
+                else if (ct == 1)
+                {
+                    if (a != B[i] || b != A[i])
+                        return false;
+                    else
+                        ++ct;
+                }
+                else
+                    return false;
+            }  
+        }
+        
+        return true;
+    }
