leetCode(50):Summary Ranges

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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"].

class Solution {
public:
    void intToString(int num, string& tmp)
    {
    	bool flag = false;
    	bool full = false;
    	if (num < 0)
    	{
    		flag = true;
    	}
    
    	if (num == 0)
    		tmp.push_back('0');
    	while (num!=0)
    	{	
    		tmp.push_back('0' + abs(num % 10));
    		num = num / 10;
    	}
    	if (flag)
    	{//最后压入负号
    		tmp.push_back('-');
    	}

//起初是将负数转换为正数，再取余，这样就不用取绝对值了（负数取余还是负数），但有一个问题，就是补码表示的正负数区间是不对称的，如-128是没问题的，可能128就不在表示范围之内了。<strong>所以不能直接将负数转换为正数</strong>。
    	reverse(tmp.begin() , tmp.end());
    }


    vector<string> summaryRanges(vector<int>& nums) {
        vector<string> result;
    	if (nums.empty())
    		return result;
    	int tmpValue;
    	string tmp;
    	bool change = false;
    	for (int i = 0; i < nums.size(); ++i)
    	{
    		if (tmp.empty())
    		{
    			intToString(nums[i], tmp);
    			tmpValue = nums[i];
    			change = false;
    		}
    		else
    		{
    			if (tmpValue + 1 == nums[i])
    			{//连续
    				tmpValue = nums[i];
    				change = true;
    			}
    			else
    			{//不连续
    				if (change)
    				{//有连续情况出现
    					tmp.push_back('-');
    					tmp.push_back('>');
    					string tmp1;
    					intToString(tmpValue, tmp1);
    					tmp+=tmp1;
    					result.push_back(tmp);
    					tmp.clear();
    					i--;
    				}
    				else
    				{//没有连续的数
    					result.push_back(tmp);
    					tmp.clear();
    					i--;
    				}
    			}
    		}
    	}
    	if (change)
    	{//最后一个string
    		tmp.push_back('-');
    		tmp.push_back('>');
    		string tmp1;
			intToString(tmpValue, tmp1);
			tmp+=tmp1;
    		result.push_back(tmp);
    		tmp.clear();
    	}
    	else
    	{
    		result.push_back(tmp);
    		tmp.clear();
    
    	}
    
    	return result;
    }
};

网上看的别人的解法，很屌！

   class Solution {
    public:
        vector<string> summaryRanges(vector<int>& nums) {
            vector<string> res;
            nums.push_back(INT_MIN);
            long long start = nums[0], last = nums[0];
            for (int i = 1; i < nums.size(); i++) {
                if (last + 1 != (long long)nums[i]) {
                    res.push_back(to_string(start));
                    if (last != start) {
                        res[res.size() - 1] = res[res.size() - 1] + "->" + to_string(last);
                    }
                    start = nums[i];
                }
                last = nums[i];
            }
            return res;
        }
    };

leetCode(50):Summary Ranges

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原文地址：http://blog.csdn.net/walker19900515/article/details/47038077