#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
/*
* Interleaving string s3 is whether a line from left top to right buttom.
* or not.
*
* s2 .....
*s1 T F F F F F
*. T F F F F F
*. T T T T T F
*. F T T F T F
* F F T T T T
* F F F T F T
*/
static bool isInterleave(char* s1, char* s2, char* s3)
{
int i, j;
int len1 = strlen(s1);
int len2 = strlen(s2);
int len3 = strlen(s3);
if (len1 + len2 != len3) {
return false;
}
bool *table = malloc((len1 + 1) * (len2 + 1) * sizeof(bool));
bool **dp = malloc((len1 + 1) * sizeof(bool *));
for (i = 0; i < len1 + 1; i++) {
dp[i] = &table[i * (len2 + 1)];
}
dp[0][0] = true;
for (i = 1; i < len1 + 1; i++) {
dp[i][0] = dp[i - 1][0] && s1[i - 1] == s3[i - 1];
}
for (i = 1; i < len2 + 1; i++) {
dp[0][i] = dp[0][i - 1] && s2[i - 1] == s3[i - 1];
}
for (i = 1; i < len1 + 1; i++) {
for (j = 1; j < len2 + 1; j++) {
bool up = dp[i - 1][j] && s1[i - 1] == s3[i + j - 1];
bool left = dp[i][j - 1] && s2[j - 1] == s3[i + j - 1];
dp[i][j] = up || left;
}
}
return dp[len1][len2];
}
int main(int argc, char **argv)
{
if (argc != 4) {
fprintf(stderr, "Usage: ./test s1 s2 s3\n");
exit(-1);
}
printf("%s\n", isInterleave(argv[1], argv[2], argv[3]) ? "true" : "false");
return 0;
}
