# Java solution beating 100%

• Some hints:

1: used a recursive function when multiple step lengths are possible

2: Used a cache, since the recursive function is called many times with the same parameters

3: if only one step length is possible (1), use iterative version (to minimize stack overflows)

4: start checking larger leaps (which are more likely to get a fast solution)

5: if the "jump" recursive function returns 1, do not invoke it with other values, since you won't get a better mark.

``````public class Solution {
int[] jumpsCache;
private int jump(int[] nums,int from) {
if(from >= nums.length - 1) return 0;
if(from + nums[from] >= nums.length - 1 ) return 1;
if(jumpsCache[from] != 0) return jumpsCache[from];
final int startFrom = from;
int directJumps = 0;
while(nums[from]==1) {
directJumps++;
from++;
if(from == nums.length - 1) {
return directJumps;
} else if(nums[from] == 0) {
return -1;
}
}
int jumps = -1;
for(int i = nums[from] ; i >= 1 ; i--) {
int nj = jump(nums,from+i);
if(nj >= 0 && (jumps == -1 || nj + 1 < jumps)) {
jumps = nj + 1;
if(nj == 1) break;
}
}
jumpsCache[startFrom] = jumps + directJumps;
return jumps + directJumps;
}
public int jump(int[] nums) {
jumpsCache = new int[nums.length];
return jump(nums,0);
}
}``````

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