# 4ms c++ in place by storing the neighbour info in board

• if current site state is dead/live, I use -1/1 to record the neighbour relation, and the relation info is stored in the board. Then, scan the board again and obtain the finial result.

``````void gameOfLife(vector<vector<int>>& board) {
int i, j, m=board.size(), n=board[0].size(), one;
for(i=0; i<m; i++) for(j=0; j<n; j++){
one=board[i][j]<=0 ? -1:1;
board[i][j]+= i-1>=0 && board[i-1][j]>0 ? one : 0;
board[i][j]+= i+1<m && board[i+1][j]>0 ? one : 0;
board[i][j]+= j-1>=0 && board[i][j-1]>0 ? one : 0;
board[i][j]+= j+1<n && board[i][j+1]>0 ? one : 0;
if(i-1>=0){
board[i][j]+=j-1>=0 && board[i-1][j-1]>0 ? one : 0;
board[i][j]+=j+1<n && board[i-1][j+1]>0 ? one : 0;
}
if(i+1<m){
board[i][j]+= j-1>=0 && board[i+1][j-1]>0 ? one : 0;
board[i][j]+= j+1<n && board[i+1][j+1]>0 ? one : 0;
}
}
for(i=0; i<m; i++) for(j=0; j<n; j++){
if(board[i][j]==-3 || board[i][j]==3 || board[i][j]==4) board[i][j]=1;
else board[i][j]=0;
}
}``````

Looks like your connection to LeetCode Discuss was lost, please wait while we try to reconnect.