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77 lines
1.9 KiB
77 lines
1.9 KiB
/**
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* File: iteration.java
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* Created Time: 2023-08-24
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* Author: krahets (krahets@163.com)
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*/
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package chapter_computational_complexity;
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public class iteration {
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/* for 迴圈 */
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static int forLoop(int n) {
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int res = 0;
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// 迴圈求和 1, 2, ..., n-1, n
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for (int i = 1; i <= n; i++) {
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res += i;
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}
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return res;
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}
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/* while 迴圈 */
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static int whileLoop(int n) {
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int res = 0;
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int i = 1; // 初始化條件變數
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// 迴圈求和 1, 2, ..., n-1, n
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while (i <= n) {
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res += i;
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i++; // 更新條件變數
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}
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return res;
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}
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/* while 迴圈（兩次更新） */
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static int whileLoopII(int n) {
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int res = 0;
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int i = 1; // 初始化條件變數
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// 迴圈求和 1, 4, 10, ...
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while (i <= n) {
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res += i;
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// 更新條件變數
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i++;
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i *= 2;
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}
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return res;
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}
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/* 雙層 for 迴圈 */
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static String nestedForLoop(int n) {
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StringBuilder res = new StringBuilder();
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// 迴圈 i = 1, 2, ..., n-1, n
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for (int i = 1; i <= n; i++) {
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// 迴圈 j = 1, 2, ..., n-1, n
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for (int j = 1; j <= n; j++) {
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res.append("(" + i + ", " + j + "), ");
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}
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}
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return res.toString();
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}
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/* Driver Code */
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public static void main(String[] args) {
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int n = 5;
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int res;
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res = forLoop(n);
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System.out.println("\nfor 迴圈的求和結果 res = " + res);
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res = whileLoop(n);
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System.out.println("\nwhile 迴圈的求和結果 res = " + res);
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res = whileLoopII(n);
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System.out.println("\nwhile 迴圈（兩次更新）求和結果 res = " + res);
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String resStr = nestedForLoop(n);
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System.out.println("\n雙層 for 迴圈的走訪結果 " + resStr);
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}
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}
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