1 files changed, 50 insertions, 0 deletions
diff --git a/2017/5.c b/2017/5.c
new file mode 100644
index 0000000..c782816
--- /dev/null
+++ b/2017/5.c
@@ -0,0 +1,50 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+
+int main(void){
+	freopen("5.in","r",stdin);
+
+	int capjumps=128,numjumps=0;
+	int *jumps=malloc(capjumps*sizeof(int));
+
+	while(true){
+		int target;
+		scanf("%d",&target);
+		if(feof(stdin))break;
+		if(numjumps==capjumps){
+			capjumps*=2;
+			jumps=realloc(jumps,capjumps*sizeof(int));
+		}
+		jumps[numjumps++]=target;
+	}
+
+	int *jumps1=malloc(numjumps*sizeof(int));
+	memcpy(jumps1,jumps,numjumps*sizeof(int));
+
+	int at=0;
+	int nsteps=0;
+	while(0<=at&&at<numjumps){
+		at+=jumps1[at]++;
+		nsteps++;
+	}
+	printf("%d\n",nsteps);
+
+	memcpy(jumps1,jumps,numjumps*sizeof(int));
+
+	at=0;
+	nsteps=0;
+	while(0<=at&&at<numjumps){
+		int next=at+jumps1[at];
+		if(jumps1[at]>=3)jumps1[at]--;
+		else jumps1[at]++;
+		at=next;
+		nsteps++;
+	}
+	printf("%d\n",nsteps);
+
+	free(jumps1);
+	free(jumps);
+}