Added some code

leetcode/problems/cpp/find-the-index-of-the-first-occurrence-in-a-string.cpp

@@ -1,26 +1,20 @@
-// by @codeAntu
-// time complexity: O(n)
-// space complexity: O(1)
+// by @codeAbinash
+// Time : O(n)
+// Space : O(1)
 
+#include "string"
+using namespace std;
 
 class Solution {
 public:
    int strStr(string haystack, string needle) {
-      int ind = 0;
-      for (int i = 0; i < haystack.size(); i++){
-         if (haystack[i] == needle[0]){
-            ind = i;
-            for (int j = 0; j < needle.size(); j++){
-               if (haystack[ind] != needle[j]){
-                  ind = 0;
-                  break;
-               }
-               ind++;
-            }
-            if (ind != 0){
-               return i;
-            }  
-         }
+      int m = haystack.size(), n = needle.size();
+      if (n == 0) return 0;
+      for (int i = 0; i <= m - n; i++) {
+         int j;
+         for (j = 0; j < n; j++)
+            if (haystack[i + j] != needle[j]) break;
+         if (j == n) return i;
       }
       return -1;
    }

leetcode/problems/cpp/repeated-substring-pattern.cpp

@@ -1,12 +1,17 @@
 // by @codeAbinash
-// Time Complexity : O(n)
-// Space Complexity : O(1n)
+
+#include "vector"
+#include "string"
+using namespace std;
 
 class Solution {
-   public:
-    bool repeatedSubstringPattern(string s) {
-        int size = s.size();
-        string str = s.substr(1, size - 1) + s.substr(0, size - 1);
-        return str.find(s) != -1;
-    }
+public:
+   bool repeatedSubstringPattern(string s) {
+      int n = s.length();
+      for (int i = n / 2; i >= 1; i--)
+         if (n % i == 0)
+            if (s.substr(0, n - i) == s.substr(i))
+               return true;
+      return false;
+   }
 };

leetcode/problems/cpp/set-matrix-zeroes.cpp

@@ -0,0 +1,37 @@
+// by @codeAbinash
+
+#include "vector"
+using namespace std;
+
+class Solution {
+public:
+   void setZeroes(vector<vector<int>>& matrix) {
+      int row = matrix.size();
+      int col = matrix[0].size();
+      bool isRowZero = false;
+
+      // Check each element and set the first row and col to 0
+      for (int i = 0; i < row; i++)
+         for (int j = 0; j < col; j++)
+            if (matrix[i][j] == 0) {
+               matrix[0][j] = 0;
+               if (i > 0)
+                  matrix[i][0] = 0;
+               else
+                  isRowZero = true;
+            }
+      // Set Zero
+      for (int i = 1; i < row; i++)
+         for (int j = 1; j < col; j++)
+            if (matrix[i][0] == 0 || matrix[0][j] == 0)
+               matrix[i][j] = 0;
+
+      if (matrix[0][0] == 0)
+         for (int i = 0; i < row; i++)
+            matrix[i][0] = 0;
+
+      if (isRowZero)
+         for (int j = 0; j < col; j++)
+            matrix[0][j] = 0;
+   }
+};

leetcode/problems/cpp/spiral-matrix.cpp

@@ -0,0 +1,37 @@
+// by @codeAbinash
+// Time : O(n)
+// Space : O(n)
+
+#include "vector"
+using namespace std;
+
+class Solution {
+public:
+   vector<int> spiralOrder(vector<vector<int>>& matrix) {
+      int left = 0, right = matrix[0].size();
+      int top = 0, bottom = matrix.size();
+      vector<int> ans;
+
+      while (top < bottom && left < right) {
+         for (int i = left; i < right; i++)
+            ans.push_back(matrix[top][i]);
+         top++;
+
+         for (int i = top; i < bottom; i++)
+            ans.push_back(matrix[i][right - 1]);
+         right--;
+
+         if (!(left < right && top < bottom))
+            break;
+
+         for (int i = right - 1; i >= left; i--)
+            ans.push_back(matrix[bottom - 1][i]);
+         bottom--;
+
+         for (int i = bottom - 1; i >= top; i--)
+            ans.push_back(matrix[i][left]);
+         left++;
+      }
+      return ans;
+   }
+};