程式語言 - LeetCode - C - 1466. Reorder Routes to Make All Paths Lead to the City Zero

參考資訊：
https://blog.csdn.net/fuxuemingzhu/article/details/106597991

題目：


解答：

#define COST 0x80000000

int travel(int **connections, int n, int *visit, int *len, int **cost, int cur)
{
    int r = 0;
    int c0 = 0;

    visit[cur] = 1;
    for (c0 = 0; c0 < len[cur]; c0++) {
        int dst = cost[cur][c0] & ~COST;

        if (visit[dst] == 0) {
            r += !!(cost[cur][c0] & COST);
            r += travel(connections, n, visit, len, cost, dst);
        }
    }
    return r;
}

int minReorder(int n, int **connections, int connectionsSize, int *connectionsColSize)
{
    int c0 = 0;
    int **cost = NULL;
    int *len = malloc(sizeof(int) * n);
    int *visit = malloc(sizeof(int) * n);

    memset(len, 0, sizeof(int) * n);
    memset(visit, 0, sizeof(int) * n);

    for (c0 = 0; c0 < connectionsSize; c0++) {
        len[connections[c0][0]] += 1;
        len[connections[c0][1]] += 1;
    }

    cost = malloc(sizeof(int *) * n);
    for (c0 = 0; c0 < n; c0++) {
        cost[c0] = malloc(sizeof(int) * len[c0]);
    }

    memset(len, 0, sizeof(int) * n);
    for (c0 = 0; c0 < connectionsSize; c0++) {
        int src = connections[c0][0];
        int dst = connections[c0][1];

        cost[src][len[src]++] = dst | COST;
        cost[dst][len[dst]++] = src;
    }

    return travel(connections, n, visit, len, cost, 0);
}