T2：中间值（median）———2019.10.15
代码：
1 #include <bits/stdc++.h> 2 3 int ri() { 4 char c = getchar(); int x = 0, f = 1; for(;c < '0' || c > '9'; c = getchar()) if(c == '-') f = -1; 5 for(;c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) - '0' + c; return x * f; 6 } 7 const int N = 5e5+50; 8 9 int a[N], b[N]; 10 11 int kth(int ta[], int sa, int tb[], int sb, int k) { 12 if (sa > sb) return kth(tb, sb, ta, sa, k); 13 if (sa == 0) return tb[k]; 14 if (k == 1) return std::min(ta[1], tb[1]); 15 int ka = std::min(sa, k/2), kb = k - ka; 16 if (ta[ka] < tb[kb]) return kth(ta+ka, sa-ka, tb, sb, k-ka); 17 return kth(ta, sa, tb+kb, sb-kb, k-kb); 18 } 19 20 int query(int la, int ra, int lb, int rb) { 21 int sa = ra-la+1, sb = rb-lb+1, siz = sa + sb; 22 return kth(a+la-1, sa, b+lb-1, sb, siz/2+1); 23 } 24 25 int main() { 26 freopen("median.in", "r", stdin); 27 freopen("median.out", "w", stdout); 28 int n, m; 29 n = ri(); m = ri(); 30 for (int i = 1; i <= n; i++) a[i] = ri(); 31 for (int i = 1; i <= n; i++) b[i] = ri(); 32 for (int opt; m--; ) { 33 opt = ri(); 34 if (opt == 2) { 35 int la = ri(), ra = ri(), lb = ri(), rb = ri(); 36 printf("%d\n", query(la, ra, lb, rb)); 37 } else { 38 int p = ri(), pos = ri(), val = ri(); 39 if (p == 0) a[pos] = val; 40 else b[pos] = val; 41 } 42 } 43 return 0; 44 } 45 /* 46 5 5 47 12 41 46 68 69 48 35 61 82 84 96 49 2 1 4 3 5 50 1 0 5 75 51 2 2 4 3 4 52 2 3 4 1 5 53 2 1 4 2 4 54 */
