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package class_2022_08_1_week;
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// 给定一个只由小写字母和数字字符组成的字符串str
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// 要求子串必须只含有一个小写字母，数字字符数量随意
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// 求这样的子串最大长度是多少
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public class Code05_LongestOneLetterManyNumberString {
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// 一个绝对正确的暴力方法
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public static int right(String s) {
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char[] str = s.toCharArray();
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int ans = 0;
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for (int i = 0; i < str.length; i++) {
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for (int j = i; j < str.length; j++) {
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if (check(str, i, j)) {
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ans = Math.max(ans, j - i + 1);
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}
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}
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}
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return ans;
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}
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public static boolean check(char[] str, int l, int r) {
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int letterNumber = 0;
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for (int i = l; i <= r; i++) {
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if (str[i] >= 'a' && str[i] <= 'z') {
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letterNumber++;
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}
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}
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return letterNumber == 1;
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}
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// 用窗口
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// 时间复杂度O(N)
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public static int zuo(String s) {
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char[] str = s.toCharArray();
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int n = str.length;
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// 窗口内有几个小写字母了
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int letters = 0;
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// 窗口的右边界
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// [left, right)
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int right = 0;
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int ans = 0;
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// for枚举了每一个窗口的开始位置，0... 1...... 2.....
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for (int left = 0; left < n; left++) {
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while (right < n) { // right不能越界，一旦越界不用再往右了
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if (letters == 1 && str[right] >= 'a' && str[right] <= 'z') {
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break;
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}
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// letters == 0 str[right]是数字
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if (str[right] >= 'a' && str[right] <= 'z') {
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letters++;
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}
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right++;
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}
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// [left.....right)
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// [left.....right-1]
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if (letters == 1) {
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ans = Math.max(ans, right - left);
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}
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if (str[left] >= 'a' && str[left] <= 'z') {
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letters--;
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}
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}
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return ans;
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}
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// 为了测试
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public static char[] chars = {
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
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'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
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'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
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'u', 'v', 'w', 'x', 'y', 'z' };
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// 为了测试
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public static String randomString(int n) {
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char[] str = new char[n];
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for (int i = 0; i < n; i++) {
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str[i] = chars[(int) (Math.random() * chars.length)];
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}
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return String.valueOf(str);
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}
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// 为了测试
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public static void main(String[] args) {
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int N = 100;
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int testTimes = 10000;
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System.out.println("测试开始");
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for (int i = 0; i < testTimes; i++) {
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int n = (int) (Math.random() * N) + 1;
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String str = randomString(n);
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int ans1 = right(str);
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int ans2 = zuo(str);
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if (ans1 != ans2) {
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System.out.println(str);
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System.out.println(ans1);
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System.out.println(ans2);
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break;
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}
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}
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System.out.println("测试结束");
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}
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}
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