#396. 种胡萝卜

https://sjzezoj.com/submission/58962

S2OJ/396/396.cpp

@@ -0,0 +1,51 @@
+// ios::sync_with_stdio(0);
+// cin.tie(nullptr);cout.tie(nullptr);
+// int n,m,ans=0;cin>>m>>n;
+// for (int i=1;i<=n;i++) fa[i]=i;
+// for (int i=1;i<=m;i++){
+// 	int x;cin>>x;int pos=find(x);
+// 	merge(pos,pos-1);(ans+=pos*i)%=mod;
+// }cout<<ans;return 0;
+
+#include <iostream>
+#include <numeric>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 3000000;
+const int mod = 1e9 + 7;
+
+int n, m, fa[N], ans;
+
+int find(int x) {
+    return fa[x] == x ? x : fa[x] = find(fa[x]);
+}
+
+void merge(int x, int y) {
+    fa[find(x)] = find(y);
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m;
+
+    std::iota(fa + 1, fa + m + 1, 1);
+
+    for (int i = 1, x; i <= n; i++) {
+        cin >> x;
+
+        int p = find(x);
+
+        merge(p, p - 1);
+
+        ans = (ans + static_cast<long long>(p) * i) % mod;
+    }
+
+    cout << ans << endl;
+
+    return 0;
+}