165 Compare Version Numbers

Author: int32bit

README.md

@@ -38,6 +38,7 @@
 + [152 Maximum Product Subarray(DP)](algorithms/MaximumProductSubarray)
 + [153 Find Minimum in Rotated Sorted Array](algorithms/FindMinimuminRotatedSortedArray)
 + [160 Intersection of Two Linked Lists](algorithms/IntersectionofTwoLinkedLists)
++ [165 Compare Version Numbers](algorithms/CompareVersionNumbers)
 + [169 Majority Element](algorithms/MajorityElement)
 + [179 Largest Number](algorithms/LargestNumber)
 + [189 Rotate Array](algorithms/RotateArray)

algorithms/CompareVersionNumbers/README.md

@@ -0,0 +1,51 @@
+## Compare Version Numbers
+
+Compare two version numbers version1 and version2.
+If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0.
+
+You may assume that the version strings are non-empty and contain only digits and the . character.
+The . character does not represent a decimal point and is used to separate number sequences.
+For instance, 2.5 is not "two and a half" or "half way to version three", it is the fifth second-level revision of the second first-level revision.
+
+Here is an example of version numbers ordering:
+
+`0.1 < 1.1 < 1.2 < 13.37`
+Credits:
+Special thanks to @ts for adding this problem and creating all test cases.
+
+## Sulution
+
+直接按`.`划分，依次比较即可，如果比较不相等后面就不需要比较了。比如`1.2.12 和 1.3.123`,当第二个子版本序列`2 < 3`，因此后面不需要比较了。
+
+注意不能用`sprintf(buf, "%f", version)`把字符串转化成浮点再比较大小，因为有可能有多个`.`,即多个子版本。
+
+## Code
+```c
+int compareVersion(char* version1, char* version2) {
+	char *p = version1;
+	char *q = version2;
+	while (*p || *q) {
+		int d1 = 0;
+		while (*p && isdigit(*p)) {
+			d1 *= 10;
+			d1 += (*p - '0');
+			p++;
+		}
+		int d2 = 0;
+		while (*q && isdigit(*q)) {
+			d2 *= 10;
+			d2 += (*q - '0');
+			q++;
+		}
+		if (d1 > d2)
+			return 1;
+		if (d1 < d2)
+			return -1;
+		if (*p)
+			p++;
+		if (*q)
+			q++;
+	}
+	return 0;
+}
+```

algorithms/CompareVersionNumbers/in.txt

@@ -0,0 +1,4 @@
+1.1.1 1.1.2
+1.2.2 1.1.1
+1.1 2.1
+1 1.2

algorithms/CompareVersionNumbers/solve.c

@@ -0,0 +1,48 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+int compareVersion(char* version1, char* version2) {
+	char *p = version1;
+	char *q = version2;
+	while (*p || *q) {
+		int d1 = 0;
+		while (*p && isdigit(*p)) {
+			d1 *= 10;
+			d1 += (*p - '0');
+			p++;
+		}
+		int d2 = 0;
+		while (*q && isdigit(*q)) {
+			d2 *= 10;
+			d2 += (*q - '0');
+			q++;
+		}
+		if (d1 > d2)
+			return 1;
+		if (d1 < d2)
+			return -1;
+		if (*p)
+			p++;
+		if (*q)
+			q++;
+	}
+	return 0;
+}
+int main(int argc, char **argv)
+{
+	char s1[20],s2[20];
+	while (scanf("%s%s", s1, s2) != EOF) {
+		switch (compareVersion(s1, s2)) {
+			case 1:
+				printf("%s > %s\n", s1, s2);
+				break;
+			case -1:
+				printf("%s < %s\n", s1, s2);
+				break;
+			default:
+				printf("%s == %s\n", s1, s2);
+		}
+	}
+	return 0;
+}