LeetCode-Algorithms-[Easy]604. 迭代压缩字符串

604. 迭代压缩字符串

一开始的做法，其实没想太多，直接就写了。。。

	public class StringIterator {
		String string;
		int i;
		int n;
		HashMap map;

		public StringIterator(String compressedString) {
			setMap();
			int n = compressedString != null ? compressedString.length() : 0;
			StringBuilder sb = new StringBuilder();
			char lastC = ' ';
			for (int i = 0; i < n; ++i) {
				char c = compressedString.charAt(i);
				if (!isNum(c)) {
					lastC = c;
					continue;
				}
				int numCount = getCount(compressedString, i, n);
				int num = strToInt(compressedString, i, numCount);
				i = i + numCount-1;
				for (int j = 0; j < num; ++j) {
					sb.append(lastC);
				}
			}
			this.string = sb.toString();
			this.n = this.string.length();
			this.i = 0;
		}

		public char next() {
			if (i < n) {
				char c = this.string.charAt(i);
				this.i++;
				return c;
			}
			return ' ';
		}

		public boolean hasNext() {
			if (i < n) {
				return true;
			}
			return false;
		}

		private int getCount(String s, int begin, int n) {
			int count = 0;
			for (int i = begin; i < n; ++i) {
				char c = s.charAt(i);
				if (isNum(c)) {
					count++;
				} else {
					break;
				}
			}
			return count;
		}

		private int strToInt(String s, int begin, int count) {
			String temp = s.substring(begin, begin + count);
			return Integer.parseInt(temp);
		}

		private boolean isNum(char c) {
			if (map.containsKey(c))
				return true;
			return false;
		}

		private void setMap() {
			this.map = new HashMap();
			map.put('1', 1);
			map.put('2', 2);
			map.put('3', 3);
			map.put('4', 4);
			map.put('5', 5);
			map.put('6', 6);
			map.put('7', 7);
			map.put('8', 8);
			map.put('9', 9);
			map.put('0', 0);
		}
	}

内存超出。。。后来想了想，其实存两个Array就行了

	public class StringIterator {
		char[] ch;
		int index;
		int[] arr;
		HashMap map;
		int size;

		public StringIterator(String compressedString) {
			setMap();
			int n = getSize(compressedString);
			initial(n);
			int l = compressedString.length();
			int b1 = 0, b2 = 0;
			for (int i = 0; i < l; ++i) {
				char c = compressedString.charAt(i);
				if (!isNum(c)) {
					ch[b1] = c;
					b1++;
				} else {
					int numCount = getCount(compressedString, i, l);
					int num = strToInt(compressedString, i, numCount);
					i = i + numCount - 1;
					arr[b2] = num;
					b2++;
				}
			}
		}

		public char next() {
			while (this.index < size && this.arr[index] <= 0) {
				index++;
			}
			if (index == size) {
				return ' ';
			}
			this.arr[index] = this.arr[index] - 1;
			return ch[index];
		}

		public boolean hasNext() {
			while (this.index < size && this.arr[index] <= 0) {
				index++;
			}
			if (this.index < this.size && arr[index] > 0) {
				return true;
			}
			return false;
		}

		private void initial(int n) {
			this.index = 0;
			this.ch = new char[n];
			this.arr = new int[n];
			this.size = n;
		}

		private boolean isNum(char c) {
			if (map.containsKey(c))
				return true;
			return false;
		}

		private void setMap() {
			this.map = new HashMap();
			map.put('1', 1);
			map.put('2', 2);
			map.put('3', 3);
			map.put('4', 4);
			map.put('5', 5);
			map.put('6', 6);
			map.put('7', 7);
			map.put('8', 8);
			map.put('9', 9);
			map.put('0', 0);
		}

		private int strToInt(String s, int begin, int count) {
			String temp = s.substring(begin, begin + count);
			return Integer.parseInt(temp);
		}

		private int getCount(String s, int begin, int n) {
			int count = 0;
			for (int i = begin; i < n; ++i) {
				char c = s.charAt(i);
				if (isNum(c)) {
					count++;
				} else {
					break;
				}
			}
			return count;
		}

		private int getSize(String s) {
			int count = 0;
			int n = s.length();
			for (int i = 0; i < n; ++i) {
				char c = s.charAt(i);
				if (!isNum(c)) {
					count++;
				}
			}
			return count;
		}
	}