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88 lines
2.8 KiB
C++
88 lines
2.8 KiB
C++
#include <cstdio>
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#include <cstring>
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inline int min(int a, int b) { return a < b ? a : b; }
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const int maxn = 10010, maxm = 4000010;
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int head[maxn], next[maxm], to[maxm], ecnt;
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inline void addEdge(int f, int t)
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{
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next[ecnt] = head[f];
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head[f] = ecnt;
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to[ecnt] = t;
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ecnt++;
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}
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int dfn[maxn], low[maxn], stk[maxn], scc[maxn], top, idx, scccnt;
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void tarjan(int x)
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{
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dfn[x] = low[x] = ++idx;
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stk[top++] = x;
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for (int i = head[x]; ~i; i = next[i])
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if (!dfn[to[i]])
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tarjan(to[i]), low[x] = min(low[x], low[to[i]]);
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else if (!scc[to[i]])
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low[x] = min(low[x], dfn[to[i]]);
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if (dfn[x] == low[x])
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{
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scccnt++;
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do
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scc[stk[--top]] = scccnt;
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while (stk[top] != x);
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}
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}
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int main()
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{
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int n, m;
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while (~scanf("%d%d", &n, &m))
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{
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memset(dfn, 0, sizeof(dfn));
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memset(low, 0, sizeof(low));
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memset(scc, 0, sizeof(scc));
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memset(head, -1, sizeof(head));
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ecnt = top = idx = scccnt = 0;
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for (int i = 0, u, v, w; i < m; ++i)
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{
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char op[5];
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scanf("%d%d%d%s", &u, &v, &w, op);
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if (op[0] == 'A')
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if (w)
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{
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addEdge(u << 1, v << 1 | 1), addEdge(v << 1, u << 1 | 1);
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addEdge(u << 1, v << 1), addEdge(v << 1 | 1, u << 1 | 1);
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addEdge(u << 1 | 1, v << 1 | 1), addEdge(v << 1, u << 1);
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}
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else
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{
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addEdge(u << 1 | 1, v << 1), addEdge(v << 1 | 1, u << 1);
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}
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if (op[0] == 'O')
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if (w)
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{
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addEdge(u << 1, v << 1 | 1), addEdge(v << 1, u << 1 | 1);
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}
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else
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{
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addEdge(u << 1, v << 1), addEdge(v << 1 | 1, u << 1 | 1);
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addEdge(u << 1 | 1, v << 1 | 1), addEdge(v << 1, u << 1);
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addEdge(u << 1 | 1, v << 1), addEdge(v << 1 | 1, u << 1);
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}
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if (op[0] == 'X')
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if (w)
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{
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addEdge(u << 1, v << 1 | 1), addEdge(v << 1, u << 1 | 1);
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addEdge(u << 1 | 1, v << 1), addEdge(v << 1 | 1, u << 1);
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}
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else
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{
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addEdge(u << 1, v << 1), addEdge(v << 1 | 1, u << 1 | 1);
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addEdge(u << 1 | 1, v << 1 | 1), addEdge(v << 1, u << 1);
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}
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}
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for (int i = 0; i < (n << 1); i++)
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if (!dfn[i]) tarjan(i);
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bool flag = true;
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for (int i = 0; i < n && flag; i++)
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if (scc[i << 1] == scc[i << 1 | 1])
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flag = false;
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puts(flag ? "YES" : "NO");
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}
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return 0;
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} |