59 lines
2.0 KiB
C++
59 lines
2.0 KiB
C++
class Solution {
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public:
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// search word[index] at locations (i,j)
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bool search(vector<vector<char>>& board, string word, int i, int j, int index){
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// base case
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if(index>=word.length()){
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// when index is equal to word length, it means our search job is done.
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// and in this case, we don't care if i or j is out of bounds of not.
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return true;
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}
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// boundary checking
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if(i<0 || i>=board.size()){
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return false;
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}
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if(j<0 || j>=board[0].size()){
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return false;
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}
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// if not equal, then this is not the path we are looking for.
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if(board[i][j] != word[index]){
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return false;
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}
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char c = board[i][j];
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// if it's found, we change it to '0' so we can guarantee to not reuse it while we are still on this path.
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board[i][j]='0';
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// general case
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// if search job is still incomplete, then let's continue searching letter i in all four directions, and if we can find the word in any of these four directions, then we are good.
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if( (search(board, word, i, j+1, index+1) ||
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search(board, word, i, j-1, index+1) ||
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search(board, word, i-1, j, index+1) ||
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search(board, word, i+1, j, index+1) ) == true ){
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return true;
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}else{
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// restore board[i][j] to its original value
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board[i][j] = c;
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return false;
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}
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}
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bool exist(vector<vector<char>>& board, string word) {
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int m=board.size();
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int n=board[0].size();
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// find the first letter of this word
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for(int i=0;i<m;i++){
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for(int j=0;j<n;j++){
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// if it's true, return true; if not, continue search at next (i,j)
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if(search(board, word, i, j, 0) == true){
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return true;
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}
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}
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}
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// if we reach here, then the word can't be found.
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return false;
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}
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};
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