Merge pull request #104 from aadityasinha-dotcom/min_Jumps

minimum jumps

Author: SarthakKeshari

GeeksForGeeks/minimum_Jumps.java

@@ -0,0 +1,56 @@
+/*
+Given an array of integers where each element represents the max number of steps that can be made forward from that element.
+Return the minimum number of jumps to reach the end of the array. If an element is 0, it cannot move through that element. If the end isn’t reachable, return -1.
+*/
+import java.util.*;
+
+public class minimum_Jumps {
+    
+    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();
+        }
+        minJumps(arr, n);
+        sc.close();
+
+    }
+    static void minJumps(int[] arr, int n){
+        int[] jumps = new int[n];
+        int min;
+        jumps[n-1] = 0;
+        for(int i = n-2; i >= 0; i--){
+            // If arr[i] is 0 then arr[n-1]
+            // can't be reached from here
+            if(arr[i]==0){
+                jumps[i] = Integer.MAX_VALUE;
+                // If we can directly reach to
+                // the end point from here then
+                // jumps[i] is 1    
+            }else if(arr[i] >= n-i-1){
+                jumps[i] = 1;
+            }else{
+                min = Integer.MAX_VALUE;
+                // following loop checks
+                // with all reachable points
+                // and takes the minimum
+                for(int j = i+1; j < n && j <= arr[i]+i; j++){
+                    if(min > jumps[i]){
+                        min = jumps[j];
+                    }
+                }
+                // Handle overflow
+                if(min!=Integer.MAX_VALUE){
+                    jumps[i] = min+1;
+                }else{
+                    jumps[i] = min;     // or Integer.MAX_VALUE
+                }
+            }
+        }
+        System.out.println(jumps[0]);
+    }
+
+}