bool canCross(int indx, int unit, vector<int>& stones, unordered_map<int, int>& stoneMap, vector<vector<bool>>& visited, vector<vector<bool>>& dp) {

if(indx == stones.size() - 1) {

return true;

}

if(indx >= stones.size()) {

return false;

}

if(visited[indx][unit]) {

return dp[indx][unit];

}

bool isReached = false;

if(stoneMap[stones[indx] + unit + 1]) {

int nextIndx = stoneMap[stones[indx] + unit + 1] - 1;

isReached |= canCross(nextIndx, unit + 1, stones, stoneMap, visited, dp);

}

if(!isReached and unit > 0 and stoneMap[stones[indx] + unit]) {

int nextIndx = stoneMap[stones[indx] + unit] - 1;

isReached |= canCross(nextIndx, unit, stones, stoneMap, visited, dp);

}

if(!isReached and unit - 1 > 0 and stoneMap[stones[indx] + unit - 1]) {

int nextIndx = stoneMap[stones[indx] + unit - 1] - 1;

isReached |= canCross(nextIndx, unit - 1, stones, stoneMap, visited, dp);

}

visited[indx][unit] = true;

return dp[indx][unit] = isReached;

}

public:

bool canCross(vector<int>& stones) {

int n = stones.size();

const int MAX_UNIT = 100;

vector<vector<bool>> dp(n, vector<bool>(MAX_UNIT, false));

vector<vector<bool>> visited(n, vector<bool>(MAX_UNIT, false));

unordered_map<int, int> stoneMap;

for(int i = 1; i <= n; ++i) {

stoneMap[stones[i - 1]] = i;

}

return canCross(0, 0, stones, stoneMap, visited, dp);

}