//leetcode submit region begin(Prohibit modification and deletion)

class Solution {

public boolean canCross(int[] stones) {

int len = stones.length;

Map<Integer, Set<Integer>> dp = new HashMap<>();

for(int i = 0; i < len; i++)

dp.put(stones[i], new HashSet<>());

dp.get(stones[0]).add(0);

for(int i = 0; i < len; i++) {

Set<Integer> set = dp.get(stones[i]);

for(int step : set) {

for(int k = step - 1; k <= step + 1; k++) {

if(k > 0 && dp.containsKey(stones[i] + k))

dp.get(stones[i] + k).add(k);

}

}

}

return !dp.get(stones[len - 1]).isEmpty();

}

}

//leetcode submit region end(Prohibit modification and deletion)

public static void main(String[] args) {

Solution solution = new FrogJump().new Solution();

}

}