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Leetcode[228] Summary Ranges

29 Nov 2015

###Task1 Given a sorted integer array without duplicates, return the summary of its ranges.

For example, given [0,1,2,4,5,7], return [“0->2”,”4->5”,”7”].

###Python ####Mine

class Solution(object):
    def summaryRanges(self, nums):
        """
        :type nums: List[int]
        :rtype: List[str]
        """
        if not nums or len(nums) == 0:
            return []
        cur = str(nums[0])
        prev = nums[0]
        ret = []
        for i in range(1, len(nums)):
            if nums[i] == prev + 1:
                prev += 1
                continue
            else:
                if int(cur) != prev:
                    cur += '->'
                    cur += str(prev)
                ret.append(cur)
                prev = nums[i]
                cur = str(nums[i])
        if int(cur) != prev:
            cur += '->'
            cur += str(prev)
        ret.append(cur)
        return ret

####Short but robust

class Solution:
    # @param {integer[]} nums
    # @return {string[]}
    def summaryRanges(self, nums):
        x, size = 0, len(nums)
        ans = []
        while x < size:
            c, r = x, str(nums[x])
            while x + 1 < size and nums[x + 1] - nums[x] == 1:
                x += 1
            if x > c:
                r += "->" + str(nums[x])
            ans.append(r)
            x += 1
        return ans

###Java

public class Solution {
    public List<String> summaryRanges(int[] nums) {
        List<String> res = new ArrayList<String>();
        if (nums == null || nums.length == 0) {
            return res;
        }
        if (nums.length == 1) {
            res.add(String.valueOf(nums[0]));
            return res;
        }
        int start = nums[0];
        for (int i = 1; i < nums.length; i++) {
            if (nums[i] != nums[i - 1] + 1) {
                StringBuilder sb = new StringBuilder();
                sb.append(start);
                if (start != nums[i - 1]) {
                    sb.append("->");
                    sb.append(nums[i - 1]);
                }
                res.add(sb.toString());
                start = nums[i];
            }
        }
        StringBuilder sb = new StringBuilder();
        sb.append(start);
        if (start != nums[nums.length - 1]) {
            sb.append("->");
            sb.append(nums[nums.length - 1]);
        }
        res.add(sb.toString());
        
        return res;
        
    }
}

###Points

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