"House Robber II"

Author: lennylxx

README.md

@@ -111,7 +111,7 @@ The `☢` means that you need to have a LeetCode Premium Subscription.
 | 216 | [Combination Sum III]                                        | [C++](src/216.cpp) |
 | 215 | [Kth Largest Element in an Array]                            | [C](src/215.c)     |
 | 214 | [Shortest Palindrome]                                        |                    |
-| 213 | [House Robber II]                                            |                    |
+| 213 | [House Robber II]                                            | [C](src/213.c)     |
 | 212 | [Word Search II]                                             | [C](src/212.c)     |
 | 211 | [Add and Search Word - Data structure design]                | [C](src/211.c)     |
 | 210 | [Course Schedule II]                                         |                    |

src/213.c

@@ -0,0 +1,38 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define max(a,b) ((a)>(b)?(a):(b))
+int robNoCircle(int num[], int n) {
+    if (n == 0) return 0;
+    int *dp = (int *)calloc(n + 2, sizeof(int));
+    int i;
+    dp[0] = dp[1] = 0; /* dummy */
+    for (i = 2; i < n + 2; i++) {
+        /* for each house, there are two choices: robbing and NOT robbing */
+        if (dp[i - 2] + num[i - 2] > dp[i - 1]) { /* rob */
+            dp[i] = dp[i - 2] + num[i - 2];
+        }
+        else { /* don't rob */
+            dp[i] = dp[i - 1];
+        }
+    }
+    int ans = dp[n + 1];
+    free(dp);
+    return ans;
+}
+
+int rob(int* nums, int numsSize) {
+    if (nums == NULL || numsSize == 0) return 0;
+    if (numsSize == 1)  return nums[0];
+    return max(robNoCircle(nums, numsSize - 1), robNoCircle(nums + 1, numsSize - 1));
+}
+
+int main() {
+    int nums[] = { 1, 2, 3, 4, 5 };
+
+    assert(rob(nums, sizeof(nums) / sizeof(nums[0])) == 8);
+
+    printf("all tests passed!\n");
+
+    return 0;
+}