java 228.摘要范围（第1个）.java

Posted 2021-05-08

List<String> list=new ArrayList();
	if(nums.length==1){
		list.add(nums[0]+"");
		return list;
	}
    for(int i=0;i<nums.length;i++){
    	int a=nums[i];
    	while(i+1<nums.length&&(nums[i+1]-nums[i])==1){
    		i++;
    	}
    	if(a!=nums[i]){
    		list.add(a+"->"+nums[i]);
    	}else{
    		list.add(a+"");
    	}
    }
    return list;

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

public class Solution {
    public List<String> summaryRanges(int[] nums) {
        List<String> res = new ArrayList<>();
        if (nums.length == 0)  return res;
        
        if (nums.length == 1) {
            res.add(nums[0] + "");
            return res;
        }
        
        int start = nums[0];
        int prev = nums[0];
        
        for (int i = 1; i < nums.length; i++) {
            int cur = nums[i];
            if (prev + 1 != cur) {
                // End
                res.add(start != prev ? start + "->" + prev : start + "");
                
                // New start
                start = cur;
            }
            prev = cur;
        }
        
        res.add(start != prev ? start + "->" + prev : start + "");
        return res;
    }
}