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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 循环 */
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int forLoop(int n) {
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int res = 0;
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// 循环求和 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 循环 */
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int whileLoop(int n) {
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int res = 0;
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int i = 1; // 初始化条件变量
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// 循环求和 1, 2, ..., n-1, n
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while (i <= n) {
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res += i;
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i++; // 更新条件变量
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}
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return res;
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}
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/* while 循环（两次更新） */
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int whileLoopII(int n) {
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int res = 0;
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int i = 1; // 初始化条件变量
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// 循环求和 1, 4, ...
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while (i <= n) {
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res += i;
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// 更新条件变量
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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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/* 双层 for 循环 */
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char *nestedForLoop(int n) {
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// n * n 为对应点数量，"(i, j), " 对应字符串长最大为 6+10*2，加上最后一个空字符 \0 的额外空间
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int size = n * n * 26 + 1;
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char *res = malloc(size * sizeof(char));
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// 循环 i = 1, 2, ..., n-1, n
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for (int i = 1; i <= n; i++) {
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// 循环 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 循环的求和结果 res = %d\n", res);
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res = whileLoop(n);
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printf("\nwhile 循环的求和结果 res = %d\n", res);
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res = whileLoopII(n);
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printf("\nwhile 循环（两次更新）求和结果 res = %d\n", res);
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char *resStr = nestedForLoop(n);
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printf("\n双层 for 循环的遍历结果 %s\r\n", resStr);
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free(resStr);
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return 0;
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}
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