demo3.txt

package chapter5;

//去掉连续出现k个0的子串
public class demo3 {

	public static void main(String[] arfs){
		String str = "000100400004000";
//		System.out.println(str.indexOf("4000"));
		System.out.println(test(str,3));
		System.out.println(test1(str,3));
	}
	public static String test1(String str,int k){
		if(k==0){
			return str;
		}
		if(str==null){
			return null;
		}
		StringBuilder sb = new StringBuilder(str);
		int count = 0;
		
		for(int i=0;i<sb.length();i++){
			if(sb.charAt(i)=='0'){
				count++;
			}
			else{
				if(count==k){
					for(int j=i-1;count>0;j--,count--){
						sb.deleteCharAt(j);
					}
				}
				//无论k和count是否相等，都要清0一下
				count = 0;
			}
		}
		//最后还要再判断一次k和count是否相等
		if(count==k){
			for(int j=sb.length()-1;count>0;j--,count--){
				sb.deleteCharAt(j);
			}
		}
		return sb.toString();
	}
	
	
	public static String test(String str,int k){
		if(k==0){
			return str;
		}
		if(str==null||str.length()==0){
			return null;
		}
		char[] arr = str.toCharArray();
		int count = 0;
		int start = -1;
		StringBuilder sb = new StringBuilder();
		
		for(int i=0;i!=arr.length;i++){
			if(arr[i] == '0'){
				count++;
				start = start==-1?i:start;
			}
			else{
				if(count==k){
					//要开始删除0
					while(count--!=0){
						arr[start++] = 0;
					}
				}
				start = -1;
				count = 0;
			}
		}
		if(count==k){
			while(count--!=0){
				arr[start++] = 0;
				
			}
		}
		
		for(int i=0;i<arr.length;i++){
			if(arr[i]!=0){
				sb.append(arr[i]);
			}
		}
		return sb.toString();
	}
}