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给定从文件中读取的用于所有测试用例的输入字典和几个单词搜索网格，我想识别字典中出现在每个单词搜索网格中的所有单词。

我已经阅读了 dictionary.txt 文件，并且我相信它可以读取任何字母网格，但我在尝试找到出现在 dictionary.txt 文件中的网格中的单词时遇到了麻烦。我决定对各个方向的字符串使用递归二进制搜索，但这对我来说有点复杂。

我的程序一直运行，直到它到达单词搜索功能，它试图在网格中找到单词，它会崩溃，但我不知道为什么，也不确定我是否在正确的轨道上。

这是我认为是错误的部分，

int binsearch(char** dictionary, char** puzzle, int low, int high){

int mid;

if(low == 0 && high == 0){
    return 0;
}

mid = (low+high)/2 ;

if(strcmp(*puzzle,dictionary[mid]) == 0){
        //found a match
    return 1;
}

else if(strcmp(*puzzle,dictionary[mid]) > 0){
        //check upper half
    return binsearch(dictionary,puzzle,mid+1,high);
}

else if(strcmp(*puzzle,dictionary[mid]) < 0){
    //check lower half
    return binsearch(dictionary,puzzle,low,mid-1);
}
else return 0;

}

char wordSearch(char** dictionary, char** puzzle, int row, int col){

int i, X, Y, dir = 0;
char* wordsfound[20]= {'\0'};
for (X=0;X<row+1;X++){
    for(Y=0;Y<col;Y++){
        for(dir=0;dir<DX_SIZE;dir++) //check every direction
            for(i=0;i<19;i++){
                //will continue in direction DX,DY starting at x,y
                int nextX = X + DX[dir] * i;
                int nextY = Y + DY[dir] * i;
                if(nextX < 0 || nextX >= row) break; //keep in bounds
                if(nextY < 0 || nextY >= col) break;
                //store the string of letters
                *wordsfound[i] = (puzzle[nextX][nextY]);
                if(i>2){ //minimum word is 3
                //if the string of letters is actually a word, print
                    int bin = binsearch(dictionary,wordsfound,1,listlength);
                    if(bin){
                        printf("%s\n",wordsfound);
                    }
                }
            }
    }
}

}

但这是我的整个代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define listlength 149256
#define maxWordLen 19


char** getWords(int rows, int cols);
void freeArray(char** array, int rows);
char** makeGridArray(int rows, int cols);
int binsearch(char** dictionary, char** puzzle, int low, int high);
char wordSearch(char** dictionary, char** puzzle, int row, int col);
const int DX_SIZE = 8;
const int DX[] = {-1,-1,-1,0,0,1,1,1};
const int DY[] = {-1,0,1,-1,1,-1,0,1};

int main(){

    //read in dictionary
    int i,j,x=0, numCases, gridRow, gridCol;
    char** words = getWords(listlength, maxWordLen);

    //Get number of cases.

    printf("enter number of cases:\n");
    scanf("%d", &numCases);

    //process each case.

    while(x < numCases){

        scanf("%d%d",&gridRow,&gridCol);

        //make word search grid
        char** grid = makeGridArray(gridRow+1, gridCol);

        /* for testing if grid is storing properly

        for(i=0; i<gridRow+1;i++){
            printf("%s\n",grid[i]);
        }

        */
        printf("Words Found Grid #%d:",x+1);
        wordSearch(words, grid, gridRow+1, gridCol);
        x++;
        freeArray(grid,gridRow+1);
    }
    freeArray(words, listlength);

}


char** getWords(int rows, int cols){

    int i;

    //allocate top level of pointers.
    char** words = malloc(sizeof(char*)*rows);

    //allocate each individual array
    for(i=0; i<rows; i++){
        words[i] = malloc(sizeof(char)*cols+1);
    }

    //read dictionary.txt
    FILE *dictionary = fopen("dictionary.txt", "r");
    for(i=0; i<rows; i++){
        fgets(words[i], cols+1,dictionary);
    }

    fclose(dictionary);
    return words;
}

char** makeGridArray(int rows, int cols){

    //allocate top level of pointers.
    char** grid = malloc(sizeof(char*)*rows);
    int i,j;

    //allocate each individual array
    for(i=0; i<rows;i++){
        grid[i] = malloc(sizeof(char)*cols+1);
    }
    //read in user input grid
    for(i=0;i<rows;i++){
        gets(grid[i]);
    }
    return grid;
}

int binsearch(char** dictionary, char** puzzle, int low, int high){

    int mid;

    if(low == 0 && high == 0){
        return 0;
    }

    mid = (low+high)/2 ;

    if(strcmp(*puzzle,dictionary[mid]) == 0){
            //found a match
        return 1;
    }

    else if(strcmp(*puzzle,dictionary[mid]) > 0){
            //check upper half
        return binsearch(dictionary,puzzle,mid+1,high);
    }

    else if(strcmp(*puzzle,dictionary[mid]) < 0){
        //check lower half
        return binsearch(dictionary,puzzle,low,mid-1);
    }
    else return 0;

}

char wordSearch(char** dictionary, char** puzzle, int row, int col){

    int i, X, Y, dir = 0;
    char* wordsfound[20]= {'\0'};
    for (X=0;X<row+1;X++){
        for(Y=0;Y<col;Y++){
            for(dir=0;dir<DX_SIZE;dir++) //check every direction
                for(i=0;i<19;i++){
                    //will continue in direction DX,DY starting at x,y
                    int nextX = X + DX[dir] * i;
                    int nextY = Y + DY[dir] * i;
                    if(nextX < 0 || nextX >= row) break; //keep in bounds
                    if(nextY < 0 || nextY >= col) break;
                    //store the string of letters
                    *wordsfound[i] = (puzzle[nextX][nextY]);
                    if(i>2){ //minimum word is 3
                    //if the string of letters is actually a word, print
                        int bin = binsearch(dictionary,wordsfound,1,listlength);
                        if(bin){
                            printf("%s\n",wordsfound);
                        }
                    }
                }
        }
    }

}


void freeArray(char** array, int rows){
    //free arrays
    int i;
    for(i=0; i<rows; i++){
        free(array[i]);
    }
    free(array);
}
4

2 回答 2

1

这里：

    char* wordsfound[20]= {'\0'};
    for (X=0;X<row+1;X++){
        for(Y=0;Y<col;Y++){
            for(dir=0;dir<DX_SIZE;dir++) //check every direction
                for(i=0;i<19;i++){
                    ...
                    *wordsfound[i] = (puzzle[nextX][nextY]);

应该：

    char wordsfound[20]= {'\0'};                    /* not 20 pointers! */
    for (X=0;X<row+1;X++){
        for(Y=0;Y<col;Y++){
            for(dir=0;dir<DX_SIZE;dir++) //check every direction
                for(i=0;i<19;i++){
                    ...
                    wordsfound[i] = (puzzle[nextX][nextY]);   /* no '*' */
                    wordsfound[i+1] = '\0';           /* end the string */

此外，在您的 binsearch 函数中，当您检查上半部分或下半部分时，您需要确保mid+1和mid-1分别仍然是数组的有效索引。如果您访问数组边界之外的元素，那么不好的事情正等着咬您。

例如，如果low = 0和high = 1：

mid = (low+high)/2 ;       /* this is zero */

所以你与数组元素 0 进行比较并决定你需要查看下半部分，现在你用 low as mid-1which is调用-1。哦不！

于 2016-02-07T07:49:07.817 回答
1

你有

char* wordsfound[20]= {'\0'};

以上仅使所有 20char pointers都指向 NULL。

然后你取消引用

*wordsfound[i] = (puzzle[nextX][nextY]);

所以，它崩溃是因为它wordsfound[i]是 NULL。

编辑： 所以，你必须改变 wordfound 的声明。如果您按照@John Hascall 和@JVA 的建议将其更改为 char wordsfound[20]，那么您需要这样做：

char wordSearch(char** dictionary, char** puzzle, int row, int col){

    int i, X, Y, dir = 0;
    char wordsfound[20]= {'\0'};
    for (X=0;X<row+1;X++){
        for(Y=0;Y<col;Y++){
            for(dir=0;dir<DX_SIZE;dir++) //check every direction
                for(i=0;i<19;i++){
                    //will continue in direction DX,DY starting at x,y
                    int nextX = X + DX[dir] * i;
                    int nextY = Y + DY[dir] * i;
                    if(nextX < 0 || nextX >= row) break; //keep in bounds
                    if(nextY < 0 || nextY >= col) break;
                    //store the string of letters
                    wordsfound[i] = (puzzle[nextX][nextY]);
                    if(i>2){ //minimum word is 3
                        wordsfound[i+1]= '\0'; // yes you need null char before passing to binsearch for strcmp to work.
                        //if the string of letters is actually a word, print
                        int bin = binsearch(dictionary, &wordsfound,1,listlength);
                        if(bin){
                           printf("%s\n",wordsfound);
                        }
                    }
                }

            }
        }

    }

即你需要传递&wordsfound给binsearch因为作为第二个参数binsearch。char **

您可以只传递wordsfound，但在这种情况下，将binsearch函数的第二个参数更改为char * puzzle并使用puzzleinstrcmp而不是*puzzleinside binsearch。

但是，如果您的目标不是像假设的 JVA 先生那样将单个字符传递给 binsearch，那么您需要采取不同的做法。在这种情况下，您需要使用二维字符数组或指向字符数组的指针。在这种情况下，您需要将当前代码更改为wordsearch. 如果使用pointer to a char array，则需要分配内存。

于 2016-02-07T07:51:50.087 回答