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/**
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* File: iteration.c
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* Created Time: 2023-09-09
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* Author: Gonglja (glj0@outlook.com), MwumLi (mwumli@hotmail.com)
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*/
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#include "../utils/common.h"
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/* for 迴圈 */
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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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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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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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char *nestedForLoop(int n) {
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// n * n 為對應點數量，"(i, j), " 對應字串長最大為 6+10*2，加上最後一個空字元 \0 的額外空間
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int size = n * n * 26 + 1;
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char *res = malloc(size * sizeof(char));
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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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char tmp[26];
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snprintf(tmp, sizeof(tmp), "(%d, %d), ", i, j);
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strncat(res, tmp, size - strlen(res) - 1);
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}
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}
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return res;
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}
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/* Driver Code */
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int main() {
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int n = 5;
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int res;
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res = forLoop(n);
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printf("\nfor 迴圈的求和結果 res = %d\n", res);
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res = whileLoop(n);
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printf("\nwhile 迴圈的求和結果 res = %d\n", res);
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res = whileLoopII(n);
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printf("\nwhile 迴圈（兩次更新）求和結果 res = %d\n", res);
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char *resStr = nestedForLoop(n);
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printf("\n雙層 for 迴圈的走訪結果 %s\r\n", resStr);
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free(resStr);
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return 0;
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}
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