Added First_Missing_Positive_Number Program

diablo1408 · diablo1408 · commit b8b4391c2843 · 2020-10-01T13:04:26.000+05:30
diff --git a/First_Missing_Positive_Number.java b/First_Missing_Positive_Number.java
@@ -0,0 +1,46 @@
+import java.util.Arrays;
+import java.util.Scanner;
+
+public class First_Missing_Positive_Number {
+
+
+    public static void main(String[] args) {
+        Scanner sc= new Scanner(System.in);
+        int N=sc.nextInt();
+        int []Arr= new int[N];
+        for( int i=0;i<N;i++)
+            Arr[i]=sc.nextInt();
+        System.out.println(firstMissingPositive(Arr));
+
+
+
+
+    }
+    static int firstMissingPositive(int[] nums) {
+        int n=nums.length;
+        int  i=0;
+        while(i<n){
+            if(nums[i]>0&&nums[i]<=n&&nums[nums[i]-1]!=nums[i]){
+                swap(i,nums[i]-1,nums)  ;
+            }
+            else
+                i++;
+        }
+        System.out.println(Arrays.toString(nums));
+
+        for(  i=0;i<n;i++){
+            if(nums[i]!=i+1){
+                return i+1;
+            }
+        }
+
+
+        return n+1;
+
+    }
+    static void swap(int x,int y,int[]A){
+        int  t=A[x];
+        A[x]=A[y];
+        A[y]=t;
+    }
+}
