Done Array-1

Diagonal traverese.cpp

@@ -0,0 +1,58 @@
+class Solution {//time compleaxity o(m*n)and space complexity o(1)
+public:
+    vector<int> findDiagonalOrder(vector<vector<int>>& mat) {
+        if(mat.size()==0)
+        return {};
+        int m =mat.size();
+        int n= mat[0].size();
+        vector<int>result(n*m);
+        bool dir =true;
+        int r =0,c=0;
+
+        for(int i=0;i<m*n;i++)
+        {
+
+           result[i] =mat[r][c];
+        if(dir)//upward
+        { 
+            if(c==n-1)// hit top edge
+            {
+             dir =false;
+             r++;
+            }
+            else if(r==0)// hit right edge
+            {
+              dir =false;
+              c++;
+            }
+            else //normal
+            {
+                r--;
+                c++;
+            }  
+
+        }
+        else//downward
+        {
+          if(r==m-1) //hit bottom edge
+          {
+             dir =true;
+             c++;
+          }
+          else if(c==0) //hit left edge
+          {
+            dir=true;
+            r++;
+          }
+          else
+          {
+            r++;
+            c--;
+          }
+
+        }
+
+    }
+    return result;
+    }
+};

Product of array except self.cpp

@@ -0,0 +1,20 @@
+class Solution {
+public:
+    vector<int> productExceptSelf(vector<int>& nums) {
+        vector<int>result;
+        result[0]=1;
+        for(int i =1;i<nums.size();i++) // calculate the left product for each element
+        {
+          result[i]= result[i-1]*nums[i-1];
+        }
+        int right = 1; // to calculate right product for each element and put in result array 
+        for(int i=result.size()-1;i>=0;i++)
+        {
+           result[i]=result[i]*right;
+           right = right*nums[i];
+           i--;
+        }
+
+        return result;
+    }
+};

spiral matrix.cpp

@@ -0,0 +1,31 @@
+class Solution {//tc:O(m*n),sc:O(1)
+public: 
+    vector<int> spiralOrder(vector<vector<int>>& matrix) {
+        if(matrix.size()==0)
+        return {};
+        int m =matrix.size();
+        int n= matrix[0].size();
+        int l =0,r=n-1,t=0,b=m-1;//left,right,top ,bottom
+        vector<int>result;
+        while(l<=r && t<=b)
+        {
+            for(int i =l;i<=r;i++)
+            result.push_back(matrix[t][i]);
+            t++;
+            for(int i =t;i<=b;i++)
+            result.push_back(matrix[i][r]);
+            r--;
+            if(t<=b){ // to avoid duplicates
+            for(int i =r;i>=l;i--)
+            result.push_back(matrix[b][i]);
+            b--;
+            }
+            if(l<=r){
+            for(int i =b;i>=t;i--)
+            result.push_back(matrix[i][l]);
+            l++;
+            }
+        }
+        return result;
+    }
+};