BZOJ1901: Zju2112 Dynamic Rankings(整体二分 树状数组)

#include<cstdio>
#include<cstring>
#include<vector>
#define lowbit(x) ((x) & (-x))
#define getchar() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1 << 21, stdin), p1 == p2) ? EOF : *p1++)
using namespace std;
const int MAXN = 1e5 + 10, INF = 1e9 + 10;
char buf[1 << 21], *p1 = buf, *p2 = buf;
inline int read() {
    char c = getchar(); int x = 0, f = 1;
    while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}
    while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();
    return x * f;
}
struct Query {
    int opt, l, r, k, id;
};
vector<Query> Q;
int N, M, a[MAXN], ans[MAXN], T[MAXN];
void Add(int pos, int val) { for(int i = pos; i <= N; i += lowbit(i)) T[i] += val;}
int Sum(int pos) {
    int ans = 0;
    for(int i = pos; i > 0; i -= lowbit(i)) ans += T[i];
    return ans;
}
void Solve(int lb, int rb, vector<Query> &Q) {
    if(Q.empty()) return ;
    if(rb - lb == 1) {
        for(int i = 0; i < Q.size(); i++)
            if(Q[i].opt == 1) 
                ans[Q[i].id] = lb;
        return ;
    }
    vector<Query>L, R;
    int mid = (lb + rb) >> 1;
    for(int i = 0; i < Q.size(); i++) {
        Query p = Q[i];
        if(p.opt == 0) {// l:pos  r:opt   k:val
            if(p.k < mid) Add(p.l, p.r), L.push_back(p);
            else R.push_back(p);
        } else {// l: Ql   R: Ql  k:you know
            int kth = Sum(p.r) - Sum(p.l - 1);
            if(kth >= p.k) L.push_back(p);
            else p.k -= kth, R.push_back(p);
        }
    }
    for(int i = 0; i < L.size(); i++) 
        if(L[i].opt == 0)
            Add(L[i].l, -L[i].r);
    Solve(lb, mid, L); Solve(mid, rb, R);
}
main() { 
    N = read(); M = read();
    for(int i = 1; i <= N; i++) Q.push_back((Query){0, i, 1, a[i] = read(), 0});
    for(int i = 1; i <= M; i++) {
        char c = '_';while(c != 'C' && c != 'Q') c = getchar();
        if(c == 'C') {
            int pos = read(), val = read();
            Q.push_back((Query){0, pos, -1, a[pos], 0});
            Q.push_back((Query){0, pos, 1, a[pos] = val, 0});
        } else {
            int ll = read(), rr = read(), kth = read();
            Q.push_back((Query){1, ll, rr, kth, i});
        }
    }
    memset(ans, -0x3f, sizeof(ans));
    Solve(0, 1e9, Q);
    for(int i = 1; i <= M; i++)
        if(ans[i] >= -INF)
            printf("%d\n", ans[i]);
    return 0;
}