Leetcode questions added

Leetcode_BestTimeToBuyAndSellStockIV.cpp

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+/*
+
+Problem No:-188
+
+You are given an integer array prices where prices[i] is the price of a given stock on the ith day, and an integer k.
+
+Find the maximum profit you can achieve. You may complete at most k transactions.
+
+Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).
+
+
+
+Example 1:
+
+Input: k = 2, prices = [2,4,1]
+Output: 2
+Explanation: Buy on day 1 (price = 2) and sell on day 2 (price = 4), profit = 4-2 = 2.
+Example 2:
+
+Input: k = 2, prices = [3,2,6,5,0,3]
+Output: 7
+Explanation: Buy on day 2 (price = 2) and sell on day 3 (price = 6), profit = 6-2 = 4. Then buy on day 5 (price = 0) and sell on day 6 (price = 3), profit = 3-0 = 3.
+
+
+Constraints:
+
+1 <= k <= 100
+1 <= prices.length <= 1000
+0 <= prices[i] <= 1000
+
+*/
+
+
+class Solution {
+public:
+    int maxProfit(int k, vector<int>& prices) {
+        if (k == 0) return 0;
+        if (k >= prices.size()/2) {
+            int s = 0;
+            for (int i = 1; i < prices.size(); ++i)
+                s += max(prices[i] - prices[i-1], 0);
+            return s;
+        }
+        vector<int> v1(k, INT_MIN);
+        vector<int> v2(k, 0);
+        for (int price : prices)
+            for (int i = 0; i < k; ++i) {
+                v1[i] = max(v1[i], (i > 0 ? v2[i-1] : 0) - price);
+                v2[i] = max(v2[i], v1[i] + price);
+            }
+        return v2.back();
+
+    }
+};

Leetcode_GenerateParanthesis.cpp

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+/*
+Problem No:- 22
+Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.
+
+Example 1:
+
+Input: n = 3
+Output: ["((()))","(()())","(())()","()(())","()()()"]
+Example 2:
+
+Input: n = 1
+Output: ["()"]
+
+Constraints:
+1 <= n <= 8
+
+*/
+
+
+class Solution {
+public:
+
+    vector<string> v;
+
+
+    void rec(int o,int c,int n,string s){
+        if(o==n && c==n){
+            v.push_back(s);
+            return;
+        }
+        else if(o==n && c<n){
+            rec(o,c+1,n,s+')');
+        }
+        else if(c>o){
+            return;
+        }
+        else if(o==c){
+            rec(o+1,c,n,s+'(');
+        }
+        else if(o>c){
+            rec(o+1,c,n,s+'(');
+            rec(o,c+1,n,s+')');
+        }
+        else
+        return;
+    }
+    vector<string> generateParenthesis(int n) {
+        rec(0,0,n,"");
+
+        return v;
+    }
+};

Leetcode_JumpGame.cpp

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+/*
+Problem No:- 55
+
+You are given an integer array nums. You are initially positioned at the array's first index, and each element in the array represents your maximum jump length at that position.
+
+Return true if you can reach the last index, or false otherwise.
+
+
+
+Example 1:
+
+Input: nums = [2,3,1,1,4]
+Output: true
+Explanation: Jump 1 step from index 0 to 1, then 3 steps to the last index.
+Example 2:
+
+Input: nums = [3,2,1,0,4]
+Output: false
+Explanation: You will always arrive at index 3 no matter what. Its maximum jump length is 0, which makes it impossible to reach the last index.
+
+
+Constraints:
+
+1 <= nums.length <= 104
+0 <= nums[i] <= 105
+
+
+*/
+
+
+class Solution {
+public:
+    bool canJump(vector<int>& nums) {
+        int m=0;
+        for(int i=0;i<nums.size();i++){
+
+            if(m>=nums.size()-1) return true;
+            if(m>=i){
+                m=max(m,i+nums[i]);
+            }
+            else if(m<i) break;
+        }
+        return false;
+    }
+};

Leetcode_UniquePath.cpp

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+/*
+Problem No:-62
+
+There is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner (i.e., grid[m - 1][n - 1]). The robot can only move either down or right at any point in time.
+
+Given the two integers m and n, return the number of possible unique paths that the robot can take to reach the bottom-right corner.
+
+The test cases are generated so that the answer will be less than or equal to 2 * 109.
+
+
+
+Example 1:
+
+
+Input: m = 3, n = 7
+Output: 28
+Example 2:
+
+Input: m = 3, n = 2
+Output: 3
+Explanation: From the top-left corner, there are a total of 3 ways to reach the bottom-right corner:
+1. Right -> Down -> Down
+2. Down -> Down -> Right
+3. Down -> Right -> Down
+
+
+Constraints:
+
+1 <= m, n <= 100
+
+*/
+
+
+class Solution {
+public:
+    int uniquePaths(int m, int n) {
+        if(m<=2){
+            if(m==1) return 1;
+            else return n;
+        }
+        if(n<=2){
+            if(n==1) return 1;
+            else return m;
+        }
+        vector<vector<int>> v(m,vector<int>(n));
+        for(int i=0;i<m;i++){
+            v[i][0]=1;
+        }
+        for(int i=0;i<n;i++){
+            v[0][i]=1;
+        }
+
+        for(int i=1;i<m;i++)
+            for(int j=1;j<n;j++)
+                  v[i][j]=v[i-1][j]+v[i][j-1];
+
+        return v[m-1][n-1];
+    }
+};