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// 1496. Path Crossing
#include "leetcode.h"
/*
* given a string 'path' where 'path[i] = 'N, 'S', 'E', or 'W', each
* representing moving one unit north, south, east, or west, respectively. you
* start at the origin '(0, 0)' on a 2d plane and walk on the path specified by
* 'path'. return 'true' if the path crosses itself at any point, that is, if at
* any time you are on a location you have previously visited. return 'false'
* otherwise.
*/
typedef struct {
uint val;
int r_type;
int c_type;
} data;
bool isPathCrossing(char *path) {
int n = strlen(path), m = 5 * n;
data **hash = calloc(m, sizeof(data *));
hash[0] = malloc(sizeof(data));
hash[0]->val = 0;
hash[0]->r_type = 1;
hash[0]->c_type = 1;
int r = 0, c = 0;
bool ans = 0;
for (int i = 0; i < n; i++) {
if (ans)
break;
switch (path[i]) {
case 'N':
r++;
break;
case 'S':
r--;
break;
case 'W':
c++;
break;
default:
c++;
}
uint val = abs(r) * 10000 + abs(c), d = val;
while (1) {
if (!hash[d % m]) {
hash[d % m] = malloc(sizeof(data));
hash[d % m]->val = val;
hash[d % m]->r_type = r >= 0;
hash[d % m]->c_type = c >= 0;
break;
} else if (hash[d % m]->val == val && hash[d % m]->r_type == r >= 0 &&
hash[d % m]->c_type == c >= 0) {
ans = 1;
break;
} else
d++;
}
}
for (int i = 0; i < m; i++)
if (hash[i])
free(hash[i]);
free(hash);
return ans;
}
int main() {
char *p1 = "NES", *p2 = "NESWW";
printf("%d\n", isPathCrossing(p1)); // expect: 0
printf("%d\n", isPathCrossing(p2)); // expect: 1
}
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