Merge pull request #364 from jyotiGambhir/jyotiGambhir

Next Similar Number Array

Author: amritansh22

Next_Similar_Number.cpp

@@ -0,0 +1,45 @@
+/*Given a number A in a form of string.You have to find the smallest number that has same set of digits as A and is greater than A.
+If A is the greatest possible number with its set of digits, then return -1.
+Problem Constraints
+1 <= A <= 10100000
+A doesn't contain leading zeroes.
+Input Format
+First and only argument is an numeric string denoting the number A.
+Output Format
+Return a string denoting the smallest number greater than A with same set of digits , if A is the largest possible then return -1.
+Example Input
+Input 1:
+A = "218765"
+Input 2:
+A = "4321"
+Example Output
+Output 1:
+"251678"
+Output 2:
+"-1"
+ */
+/*Approach: Check from back if it is in non increasing  sequence once we get the point that breaks the sequence
+find a digit that is just next greater than the current digit and swap it. Sort the digits after the current digit*/
+#include<bits/stdc++.h>
+using namespace std;
+
+string solve(string A) {
+    int pt=A.length()-2;
+    for(; pt>=0; pt--)
+        if(A[pt]<A[pt+1])
+            break;
+    if(pt==-1)
+        return "-1";
+    sort(A.begin()+pt+1, A.end());
+    int m = upper_bound(A.begin()+pt+1, A.end(), A[pt]) - A.begin();
+    swap(A[pt], A[m]);
+    
+    return A;
+}
+
+int main(){
+    string A = "218765";
+    cout<<solve(A)<<endl;
+    string B = "4321";
+    cout<<solve(B)<<endl;
+}