'commit'

TangDou/AcWing_TiGao/T4/239_DaiQuan_Static_ErFen.cpp

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+#include <bits/stdc++.h>
+using namespace std;
+const int N = 20010;
+
+// 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;
+}
+
+// 带边权更新并查集模板
+int p[N], d[N];
+int find(int x) {
+    if (x == p[x]) return x;
+    int root = find(p[x]);
+    d[x] += d[p[x]];
+    return p[x] = root;
+}
+
+int main() {
+    scanf("%d %d", &n, &m);
+    n = 0;                                // 序列的长度没有用处，我们只关心每个a,b范围内的数字1的个数
+    for (int i = 1; i < N; i++) p[i] = i; // 初始化并查集
+
+    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;
+        // 类前缀和
+        a = get(a - 1), b = get(b);
+        int t = 0;         // 偶数个1
+        if (e == 1) t = 1; // 奇数个1
+
+        // 并查集
+        int pa = find(a), pb = find(b);
+        if (pa == pb) {
+            if (abs(d[a] - d[b]) % 2 != t) {
+                res = i - 1; // 最后一条正确的序号
+                break;
+            }
+        } else {
+            p[pa] = pb;
+            d[pa] = abs(d[a] - d[b] - t) % 2;
+        }
+    }
+    printf("%d\n", res);
+    return 0;
+}