'commit'

TangDou/AcWing_TiGao/T4/239_ExtendDomain_Static_ErFen.cpp

@@ -0,0 +1,74 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+const int N = 40010, B = N / 2;
+
+// 结构体记录原始输入
+struct Node {
+    int x, y, e;
+} g[N];
+
+int n, m;
+
+// 离散化静态数组+二分查找新位置
+int b[N], bl;
+int get(int x) {
+    return lower_bound(b, b + bl, x) - b;
+}
+
+// 并查集
+int p[N];
+int find(int x) {
+    if (p[x] != x) p[x] = find(p[x]);
+    return p[x];
+}
+
+int main() {
+    scanf("%d %d", &n, &m);
+    n = 0;
+    for (int i = 1; i < N; i++) p[i] = i;
+
+    for (int i = 1; i <= m; i++) {
+        int x, y;
+        char t[100];
+        scanf("%d %d %s", &x, &y, t);
+
+        g[i].x = x, g[i].y = y;
+        if (t[0] == 'e')
+            g[i].e = 0;
+        else
+            g[i].e = 1;
+
+        // 记录下来
+        b[bl++] = x, b[bl++] = y;
+    }
+
+    // 离散化去重
+    sort(b, b + 2 * m);
+    bl = unique(b, b + 2 * m) - b;
+
+    int res = m;
+    for (int i = 1; i <= m; i++) {
+        int a = g[i].x, b = g[i].y, e = g[i].e;
+        a = get(a - 1), b = get(b);       // 计算出新的在并查集中的号
+        if (e == 0) {                     // 偶数个1
+            if (find(a + B) == find(b)) { // 如果奇偶性不同，因为b与a+B相同
+                res = i - 1;
+                break;
+            }
+            // join两个奇偶相同的集合
+            p[find(a)] = find(b);
+            p[find(a + B)] = find(b + B);
+        } else { // 奇数个1
+            if (find(a) == find(b)) {
+                res = i - 1;
+                break;
+            }
+            // join两个奇偶不相同的集合
+            p[find(a + B)] = find(b);
+            p[find(a)] = find(b + B);
+        }
+    }
+    printf("%d\n", res);
+    return 0;
+}