algorithm-class/算法周更班/class_2022_02_2_week/Code02_DesignBitset.java

package class_2022_02_2_week;

// 测试链接 : https://leetcode-cn.com/problems/design-bitset/
public class Code02_DesignBitset {

	class Bitset {

		// size int 32 
		// size / 32 向上取整
		private int[] bits;
		private final int size;
		private int zeros;
		private int ones;
		private boolean reverse;

		public Bitset(int n) {
			bits = new int[(n + 31) / 32];
			size = n;
			zeros = n;
			ones = 0;
			reverse = false;
		}

		// 把idx位置的状态，如果是0，变成1；如果是1，没有变化！
		public void fix(int idx) {
			int index = idx / 32;
			int bit = idx % 32;
			if (!reverse) {
				if ((bits[index] & (1 << bit)) == 0) {
					zeros--;
					ones++;
					bits[index] |= (1 << bit);
				}
			} else {
				if ((bits[index] & (1 << bit)) != 0) {
					zeros--;
					ones++;
					bits[index] ^= (1 << bit);
				}
			}
		}

		// 1 > 0
		public void unfix(int idx) {
			int index = idx / 32;
			int bit = idx % 32;
			if (!reverse) {
				if ((bits[index] & (1 << bit)) != 0) {
					ones--;
					zeros++;
					bits[index] ^= (1 << bit);
				}
			} else {
				if ((bits[index] & (1 << bit)) == 0) {
					ones--;
					zeros++;
					bits[index] |= (1 << bit);
				}
			}
		}

		// 0变1，1变0
		public void flip() {
			reverse = !reverse;
			int tmp = zeros;
			zeros = ones;
			ones = tmp;
		}

		// 是不是所有的位都是1
		public boolean all() {
			return ones == size;
		}

		// 是不是至少有1位是1
		public boolean one() {
			return ones > 0;
		}

		// 返回1的数量！
		public int count() {
			return ones;
		}

		public String toString() {
			StringBuilder builder = new StringBuilder();
			for (int i = 0; i < size; i++) {
				int status = bits[i / 32] & (1 << (i % 32));
				builder.append(reverse ? (status == 0 ? '1' : '0') : (status == 0 ? '0' : '1'));
			}
			return builder.toString();
		}
	}

}