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package class027;
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public class Code01_MinSwapStep {
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// 一个数组中只有两种字符'G'和'B'，想让所有的G都放在左侧，所有的B都放在右侧
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// 但是只能在相邻字符之间进行交换操作，请问请问至少需要交换几次，
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public static int minSteps1(String s) {
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if (s == null || s.equals("")) {
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return 0;
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}
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char[] str = s.toCharArray();
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int step1 = 0;
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int gi = 0;
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for (int i = 0; i < str.length; i++) {
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if (str[i] == 'G') {
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step1 += i - (gi++);
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}
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}
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int step2 = 0;
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int bi = 0;
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for (int i = 0; i < str.length; i++) {
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if (str[i] == 'B') {
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step2 += i - (bi++);
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}
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}
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return Math.min(step1, step2);
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}
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public static int minSteps2(String s) {
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if (s == null || s.equals("")) {
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return 0;
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}
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char[] str = s.toCharArray();
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int step1 = 0;
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int step2 = 0;
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int gi = 0;
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int bi = 0;
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for (int i = 0; i < str.length; i++) {
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if (str[i] == 'G') {
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step1 += i - (gi++);
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} else {
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step2 += i - (bi++);
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}
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}
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return Math.min(step1, step2);
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}
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// 为了测试
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public static String randomString(int maxLen) {
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char[] str = new char[(int) (Math.random() * maxLen)];
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for (int i = 0; i < str.length; i++) {
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str[i] = Math.random() < 0.5 ? 'G' : 'B';
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}
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return String.valueOf(str);
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}
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public static void main(String[] args) {
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int maxLen = 100;
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int testTime = 1000000;
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System.out.println("测试开始");
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for (int i = 0; i < testTime; i++) {
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String str = randomString(maxLen);
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int ans1 = minSteps1(str);
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int ans2 = minSteps2(str);
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if (ans1 != ans2) {
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System.out.println("Oops!");
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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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} |
