🚀 02-Jul-2020

Author: sureshmangs

array/binary_search.cpp

@@ -0,0 +1,69 @@
+
+/*
+Given a sorted array arr[] of N integers and a number K is given. The task is to check if the element K is present in the array or not.
+
+Input:
+First line of input contains number of testcases T. For each testcase, first line of input contains number of elements in the array and the number K seperated by space. Next line contains N elements.
+
+Output:
+For each testcase, if the element is present in the array print "1" (without quotes), else print "-1" (without quotes).
+
+Constraints:
+1 <= T <= 100
+1 <= N <= 106
+1 <= K <= 106
+1 <= arr[i] <= 106
+
+Example:
+Input:
+2
+5 6
+1 2 3 4 6
+5 2
+1 3 4 5 6
+
+Output:
+1
+-1
+
+Explanation:
+Testcase 1: Since, 6 is present in the array at index 4 (0-based indexing), so output is 1.
+Testcase 2: Since, 2 is not present in the array, so output is -1.
+*/
+
+
+
+
+
+
+
+#include<bits/stdc++.h>
+using namespace std;
+
+int bSearch(int a[], int n, int item){
+    int l=0, r=n-1, mid;
+    while(l<=r){
+        mid=l+(r-l)/2;
+        if(a[mid]==item) return 1; // found
+        else if(a[mid]>item) r=mid-1;
+        else l=mid+1;
+    }
+    return -1;
+}
+
+int main(){
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    cout.tie(NULL);
+    int t;
+    cin>>t;
+    while(t--){
+        int n, item;
+        cin>>n>>item;
+        int a[n];
+        for(int i=0;i<n;i++) cin>>a[i];
+        cout<<bSearch(a, n, item)<<endl;
+    }
+
+return 0;
+}

array/first_and_last_occurence_of_element_binary_search.cpp

@@ -0,0 +1,85 @@
+/*
+Given a sorted array with possibly duplicate elements, the task is to find indexes of first and last occurrences of an element x in the given array.
+
+Note: If the number x is not found in the array just print '-1'.
+
+Input:
+The first line consists of an integer T i.e number of test cases. The first line of each test case contains two integers n and x. The second line contains n spaced integers.
+
+Output:
+Print index of the first and last occurrences of the number x with a space in between.
+
+Constraints:
+1<=T<=100
+1<=n,a[i]<=1000
+
+Example:
+Input:
+2
+9 5
+1 3 5 5 5 5 67 123 125
+9 7
+1 3 5 5 5 5 7 123 125
+
+Output:
+2 5
+6 6
+*/
+
+
+
+
+
+
+
+#include<bits/stdc++.h>
+using namespace std;
+
+int first(int a[], int n, int item){
+    int l=0, r=n-1, mid, res=-1;
+    while(l<=r){
+        mid=l+(r-l)/2;
+        if(a[mid]==item){
+            res=mid;    // can be a possible result
+            r=mid-1;
+        }
+        else if(a[mid]<item) l=mid+1;
+        else r=mid-1;
+    }
+    return res;
+}
+
+int last(int a[], int n, int item){
+    int l=0, r=n-1, mid, res=-1;
+    while(l<=r){
+        mid=l+(r-l)/2;
+        if(a[mid]==item){
+            res=mid;    // can be a possible result
+            l=mid+1;
+        }
+        else if(a[mid]<item) l=mid+1;
+        else r=mid-1;
+    }
+    return res;
+}
+
+int main(){
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    cout.tie(NULL);
+    int t;
+    cin>>t;
+    while(t--){
+        int n, item;
+        cin>>n>>item;
+        int a[n];
+        for(int i=0;i<n;i++) cin>>a[i];
+        int f=first(a, n, item);
+        int l=last(a, n, item);
+        if(f>=0)
+            cout<<f<<" "<<l<<endl;
+        else cout<<"-1"<<endl;
+    }
+
+return 0;
+}

competitive programming/leetcode/2020-July-Challenge/Day-01-Arranging Coins.cpp

@@ -0,0 +1,47 @@
+You have a total of n coins that you want to form in a staircase shape, where every k-th row must have exactly k coins.
+
+Given n, find the total number of full staircase rows that can be formed.
+
+n is a non-negative integer and fits within the range of a 32-bit signed integer.
+
+Example 1:
+
+n = 5
+
+The coins can form the following rows:
+¤
+¤ ¤
+¤ ¤
+
+Because the 3rd row is incomplete, we return 2.
+Example 2:
+
+n = 8
+
+The coins can form the following rows:
+¤
+¤ ¤
+¤ ¤ ¤
+¤ ¤
+
+Because the 4th row is incomplete, we return 3.
+
+
+
+
+
+
+
+
+class Solution {
+public:
+    int arrangeCoins(int n) {
+        int full=0, i=1;
+        while(n>=0){
+            n-=i;
+            if(n>=0) full++;
+            i++;
+        }
+        return full;
+    }
+};

competitive programming/leetcode/441. Arranging Coins.cpp

@@ -0,0 +1,47 @@
+You have a total of n coins that you want to form in a staircase shape, where every k-th row must have exactly k coins.
+
+Given n, find the total number of full staircase rows that can be formed.
+
+n is a non-negative integer and fits within the range of a 32-bit signed integer.
+
+Example 1:
+
+n = 5
+
+The coins can form the following rows:
+¤
+¤ ¤
+¤ ¤
+
+Because the 3rd row is incomplete, we return 2.
+Example 2:
+
+n = 8
+
+The coins can form the following rows:
+¤
+¤ ¤
+¤ ¤ ¤
+¤ ¤
+
+Because the 4th row is incomplete, we return 3.
+
+
+
+
+
+
+
+
+class Solution {
+public:
+    int arrangeCoins(int n) {
+        int full=0, i=1;
+        while(n>=0){
+            n-=i;
+            if(n>=0) full++;
+            i++;
+        }
+        return full;
+    }
+};