Interleaving string

Signed-off-by: begeekmyfriend <[email protected]>

097_interleaving_string/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test interleaving_string.c

097_interleaving_string/interleaving_string.c

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+#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);
+    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;
+}