200.c

#include<stdio.h>
#include<stdbool.h>
#include<stdlib.h>
#include<string.h>

voiddfs(char**grid, bool**visited, inti, intj, intnumRows, intnumColumns) {
if (i >= 0&&i<numRows&&j >= 0&&j<numColumns&& !visited[i][j]) {
visited[i][j] =1;
if (grid[i][j] =='1') { /* island */
dfs(grid, visited, i, j-1, numRows, numColumns); /* left */
dfs(grid, visited, i, j+1, numRows, numColumns); /* right */
dfs(grid, visited, i-1, j, numRows, numColumns); /* up */
dfs(grid, visited, i+1, j, numRows, numColumns); /* down */
 }
 }
}

intnumIslands(char**grid, intnumRows, intnumColumns) {
if (grid==NULL||numRows==0||strlen(grid[0]) ==0)
return0;

inti, j;
intcount=0;

bool**visited= (bool**)calloc(numRows, sizeof(bool*));
for (i=0; i<numRows; i++) {
visited[i] = (bool*)calloc(numColumns, sizeof(bool));
 }

for (i=0; i<numRows; i++) {
for (j=0; j<numColumns; j++) {
if (!visited[i][j]) { /* has not been visited */
if (grid[i][j] =='1') /* it's an island */
count++;
dfs(grid, visited, i, j, numRows, numColumns);
 }
 }
 }
returncount;
}

intmain() {
introw=3;
intcol=3;
char**grid= (char**)calloc(1, sizeof(char*));

grid[0] ="111";
grid[1] ="010";
grid[2] ="111";

/* should be 1 */
printf("%d\n", numIslands(grid, row, col));
return0;
}