From http://blog.csdn.net/qq_33765907/article/details/51228610

ZOJ/3941_csdn.cpp

@@ -0,0 +1,50 @@
+#include <bits/stdc++.h>
+using namespace std;
+typedef pair<int, int> PII;
+const int MAXN = 100 + 10;
+
+PII P[MAXN];
+int n, m, k;
+
+void run() {
+  cin >> n >> k >> m;
+  for (int i = 0; i < n; ++i) {
+    cin >> P[i].first >> P[i].second;
+  }
+  sort(P, P + n);
+  int s = 0, ret = 0;
+  for (int i = 1; i < n; ++i) {
+    if (P[i].first <= P[s].second + 1) {
+      P[s].second = max(P[s].second, P[i].second);
+    } else P[++s] = P[i];
+  }
+  n = s + 1; s = 1 << n;
+  for (int msk = 0; msk < s; ++msk) {
+    int sum = 0, now = 0, rest = m;
+    for (int i = 0; i < n && rest; ++i) {
+      now = max(now, P[i].first - 1);
+      if (now >= P[i].second && (msk >> i & 1)) {
+        sum += P[i].second + k - 1 - now;
+        now = P[i].second + k - 1;
+        rest--;
+      } else if (now < P[i].second) {
+        int t = min(rest, (P[i].second - now - 1) / k + 1);
+        sum += t * k; now += t * k; rest -= t;
+        assert(now >= P[i].second || rest == 0);
+        if (rest && (msk >> i & 1)) {
+          sum += P[i].second + k - 1 - now;
+          now = P[i].second + k - 1;
+          rest--;
+        }
+      }
+    }
+    ret = max(ret, sum);
+  }
+  cout << ret << endl;
+}
+
+int main() {
+  int T; scanf("%d", &T);
+  for (int cas = 1; cas <= T; ++cas) run();
+  return 0;
+}