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| 1 | +/* |
| 2 | + * Copyright (C) 2022, Saul Lawliet <october dot sunbathe at gmail dot com> |
| 3 | + * All rights reserved. |
| 4 | + * |
| 5 | + * 两个指针, 模拟实际操作过程即可 |
| 6 | + * 第一次提交的时候, 没有这个情况: ".L.R." |
| 7 | + */ |
| 8 | + |
| 9 | +#include <stdbool.h> |
| 10 | +#include "c/test.h" |
| 11 | + |
| 12 | +char *pushDominoes(char *dominoes) { |
| 13 | + int slow = 0, fast = 0; |
| 14 | + |
| 15 | + for (; dominoes[fast] != '0円'; fast++) { |
| 16 | + if (dominoes[fast] == 'L') { |
| 17 | + if (dominoes[slow] == 'L' || dominoes[slow] == '.') { |
| 18 | + // all set 'L' |
| 19 | + while (slow < fast) dominoes[slow++] = 'L'; |
| 20 | + } else { |
| 21 | + // 此时是R, 向中间靠拢 |
| 22 | + int mid = (fast + slow) / 2; |
| 23 | + bool even = (fast + slow) % 2 == 0; |
| 24 | + while (slow < mid) dominoes[slow++] = 'R'; |
| 25 | + |
| 26 | + if (even) |
| 27 | + slow++; |
| 28 | + else |
| 29 | + dominoes[slow++] = 'R'; |
| 30 | + |
| 31 | + while (slow < fast) dominoes[slow++] = 'L'; |
| 32 | + } |
| 33 | + } else if (dominoes[fast] == 'R') { |
| 34 | + if (dominoes[slow] == 'L' || dominoes[slow] == '.') { |
| 35 | + // 忽略 |
| 36 | + slow = fast; |
| 37 | + } else { |
| 38 | + // all set 'R' |
| 39 | + while (slow < fast) dominoes[slow++] = 'R'; |
| 40 | + } |
| 41 | + } |
| 42 | + } |
| 43 | + |
| 44 | + // 注意, 如何最后一次操作是‘R’, 要把后面都推倒 |
| 45 | + if (dominoes[slow] == 'R') { |
| 46 | + while (slow < fast) dominoes[slow++] = 'R'; |
| 47 | + } |
| 48 | + |
| 49 | + return dominoes; |
| 50 | +} |
| 51 | + |
| 52 | +void test(const char *expect, const char *dominoes) { |
| 53 | + int len = strlen(dominoes) + 1; |
| 54 | + char *str = malloc(sizeof(char) * len); |
| 55 | + memcpy(str, dominoes, len); |
| 56 | + |
| 57 | + EXPECT_EQ_STRING_AND_FREE_ACTUAL(expect, pushDominoes(str)); |
| 58 | +} |
| 59 | + |
| 60 | +int main(void) { |
| 61 | + test("RR.L", "RR.L"); |
| 62 | + test("LL.RR.LLRRLL..", ".L.R...LR..L.."); |
| 63 | + |
| 64 | + test("LL.RR", ".L.R."); |
| 65 | + |
| 66 | + return testOutput(); |
| 67 | +} |
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