UVALive 6953Digi Comp II

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拓扑排序，顺便记录一下答案

#include<cstdio>#include<ctime>#include<queue>#include<cstring>#include<iostream>#include<algorithm>using namespace std;typedef long long LL;const int maxn = 500015;LL n, sum[maxn], T, m, flag[maxn], in[maxn];int L[maxn], R[maxn];char s[8];int main(){while (cin >> n >> m){for (int i = 0; i <= m; i++) sum[i] = in[i] = 0;for (int i = 1; i <= m; i++){scanf("%s%d%d", s, &L[i], &R[i]);flag[i] = s[0] == 'L' ? 1 : 0;++in[L[i]];++in[R[i]];}queue<int> p;for (int i = 1; i <= m; i++) if (!in[i]) p.push(i);sum[1] = n;while (!p.empty()){int q = p.front();p.pop();if (L[q]){if (--in[L[q]] == 0) p.push(L[q]);sum[L[q]] += (sum[q] + flag[q]) >> 1;}if (R[q]){if (--in[R[q]] == 0) p.push(R[q]);sum[R[q]] += (sum[q] + 1 - flag[q]) >> 1;}flag[q] ^= (sum[q] & 1);}for (int i = 1; i <= m; i++)if (flag[i]) putchar('L'); else putchar('R');putchar(10);}return 0;}