Week_1_Sejal.Aloria

Week1/Count Negative Nos/Sejal Aloria

@@ -0,0 +1,14 @@
+class Solution {
+public:
+    int countNegatives(vector<vector<int>>& grid) {
+        int count = 0;
+
+        for(int i=0;i<grid.size();i++){
+            for(int j=0;j<grid[i].size();j++){
+                if(grid[i][j]<0)
+                    count++;
+            }
+        }
+        return count;
+    }
+};

Week1/Count and Say/Sejal Aloria

@@ -0,0 +1,21 @@
+class Solution {
+public:
+    string countAndSay(int n) {
+        string s = "1";
+        while(--n){
+            string newstring;
+            int i=0;
+            while(i<s.size()){
+                int count = 1;
+                while(i+1 < s.size() && s[i]==s[i+1]){
+                    i++;
+                    count++;
+                }
+                newstring += to_string(count)+s[i];
+                i++;
+            }
+            s = newstring;
+        }
+        return s;
+    }
+};

Week1/Max Subarray/Sejal Aloria

@@ -0,0 +1,12 @@
+class Solution {
+public:
+    int maxSubArray(vector<int>& nums) {
+        int cs=nums[0];
+        int ms=nums[0];
+        for(int i=1;i<nums.size();i++){
+           ms = max(nums[i], ms + nums[i]);
+        cs = max(cs,ms);
+    }
+        return cs;
+}
+};

Week1/Missing no/Sejal Aloria

@@ -0,0 +1,12 @@
+class Solution {
+public:
+    int missingNumber(vector<int>& nums) {
+        int n = nums.size();
+        int sum=0;
+        int calsum = n*(n+1)/2;
+        for(int i=0;i<nums.size();i++){
+            sum=sum+nums[i];
+        }
+        return calsum-sum;
+    }
+};

Week1/Monotonic Array/Sejal Aloria

@@ -0,0 +1,11 @@
+class Solution {
+public:
+    bool isMonotonic(vector<int>& A)
+    {
+        auto inc = (A.front() <= A.back());
+        for (int i=1; i<A.size(); ++i)
+            if ((A[i] < A[i-1] && inc) || (A[i] > A[i-1] && !inc))
+                return false;    
+        return true;
+    }
+};

Week1/Move Zeroes/Sejal Aloria

@@ -0,0 +1,22 @@
+class Solution {
+public:
+    void moveZeroes(vector<int>& nums) {
+       int numszero = 0;
+        for(int i=0;i<nums.size();i++){
+            if(nums[i]==0)
+                numszero++;
+        }
+        vector<int>ans;
+        for(int i=0;i<nums.size();i++){
+            if(nums[i]!=0)
+                ans.push_back(nums[i]);
+        }
+        while(numszero--){
+            ans.push_back(0);
+        }
+
+        for(int i=0;i<nums.size();i++){
+            nums[i]=ans[i];
+        }
+    }
+};

Week1/Pascal Triangle/Sejal Aloria

@@ -0,0 +1,15 @@
+class Solution {
+public:
+    vector<vector<int>> generate(int numRows) {
+        vector<vector<int>>ans;
+        for(int i=0;i<numRows;i++){
+            vector<int>row(i+1,1);
+            for(int j=1;j<i;j++){
+                row[j] = ans[i-1][j] + ans[i-1][j-1];
+
+            }
+            ans.push_back(row);
+        }
+        return ans;
+    }
+};

Week1/Pivot Index/Sejal Aloria

@@ -0,0 +1,17 @@
+class Solution {
+public:
+    int pivotIndex(vector<int>& nums) {
+        int sum = 0;
+        for(int i:nums){
+            sum+=i;
+        }
+        int left = 0;
+        for(int i=0;i<nums.size();i++){
+            if(sum-left-nums[i]==left){
+                return i;
+            }
+            left+=nums[i];
+        }
+        return -1;
+    }
+};

Week1/Product Of Array/Sejal Aloria

@@ -0,0 +1,18 @@
+class Solution {
+public:
+    vector<int> productExceptSelf(vector<int>& nums) {
+        int n = nums.size();
+        int left = 1, right = 1;
+        vector<int>v;
+        for(int i=0;i<n;i++){
+            v.push_back(left);
+            left=left*nums[i];
+        }
+        for(int i=n-1;i>=0;i--){
+            v[i]=v[i]*right;
+            right=right*nums[i];
+        }
+        return v;
+
+    }
+};

Week1/Remove Duplicates/Sejal Aloria

@@ -0,0 +1,7 @@
+class Solution {
+public:
+    int removeDuplicates(vector<int>& nums) {
+    return unique(nums.begin(), nums.end()) - nums.begin();
+
+    }
+};

Week1/Rotate Array/Sejal Aloria

@@ -0,0 +1,11 @@
+class Solution {
+public:
+    void rotate(vector<int>& nums, int k) {
+        int n=nums.size();
+        k = k%n;
+        reverse(nums.begin(),nums.begin()+n-k);
+        reverse(nums.begin()+n-k,nums.end());
+        reverse(nums.begin(),nums.end());
+
+    }
+};

Week1/Spiral Matrix/Sejal Aloria

@@ -0,0 +1,41 @@
+class Solution {
+public:
+    vector<int> spiralOrder(vector<vector<int>>& matrix) {
+
+       /*t->*/ int startrow = 0, /*b->*/ endrow = matrix.size();
+       /*L->*/ int startcol = 0, /*r->*/ endcol = matrix[0].size();
+        vector<int>res;
+
+        while(startrow<endrow and startcol<endcol){
+
+            //startrow
+            for(int i=startcol;i<endcol;i++)
+                res.push_back(matrix[startrow][i]);
+            startrow++;
+            if(startrow==endrow)
+                break;
+
+
+            //endcol
+            for(int i=startrow;i<endrow;i++)
+                res.push_back(matrix[i][endcol-1]);
+            endcol--;
+            if(startcol==endcol)
+                break;
+
+            //endrow
+            for(int i=endcol-1;i>=startcol;i--)
+                res.push_back(matrix[endrow-1][i]);
+            endrow--;
+            if(startrow==endrow)
+                break;
+
+            //startcol
+            for(int i=endrow-1;i>=startrow;i--)
+                res.push_back(matrix[i][startcol]);
+            startcol++;
+
+        }
+        return res;
+    }
+};

Week1/Target Array/Sejal Aloria

@@ -0,0 +1,10 @@
+class Solution {
+public:
+    vector<int> createTargetArray(vector<int>& nums, vector<int>& index) {
+        vector<int>ans;
+        for(int i=0;i<index.size();i++){
+            ans.emplace(ans.begin()+index[i],nums[i]);
+        }
+        return ans;
+    }
+};

Week1/Valid Palindrome/Sejal Aloria

@@ -0,0 +1,19 @@
+class Solution {
+public:
+    bool isPalindrome(string s) {
+    int i=0, j=s.size()-1;
+        while(i<j){
+            if(!isalnum(s[i]))
+                i++;
+            if(!isalnum(s[j]))
+                j--;
+            if(isalnum(s[i]) && isalnum(s[j])){
+                if(tolower(s[i])!=tolower(s[j]))
+                    return false;
+                i++;
+                j--;
+            }   
+        }
+        return true;
+}
+};

Week1/Xor operation/Sejal Aloria

@@ -0,0 +1,12 @@
+class Solution {
+public:
+    int xorOperation(int n, int start) {
+        int nums[n];
+        int ans=0;
+        for(int i=0;i<n;i++){
+        nums[i] = start + 2*i;
+        ans = ans^nums[i];
+        }
+        return ans;
+    }
+};