有奖求调！！！

T3 求调，12：00 之前调成功悬一袋红烧牛肉面

#include<bits/stdc++.h>
#define Type int
#define qr(x) x=read()
typedef long long ll;
using namespace std;

inline Type read(){
    char c=getchar(); Type x=0;
    while(!isdigit(c))c=getchar();
    while(isdigit(c))x=(x<<1)+(x<<3)+(c^48),c=getchar();
    return x;
}

const int N = 2e5 + 10;
const int mod = 1e9 + 7;

int n, q, f[N];
char s[N];

int P(char A, char B){
    if(A == '#' or B == '@') return 1;
    if(A == B) return 0;
    if(A == 'R'){
        if(B == 'S') return 1;
        else return -1;
    }
    else if(A == 'S'){
        if(B == 'P') return 1;
        else return -1;
    }
    else{
        if(B == 'R') return 1;
        else return -1;
    }
}
struct tree{
        int v, pos, tag;

        bool operator < (const tree &A) const{
            return v < A.v;
        }
    }t[N<<3];
namespace Tree
{
    #define lson rt<<1
    #define rson rt<<1|1
    
    inline void pushup(int rt){
        if(t[lson].v < t[rson].v) t[rt].v = t[lson].v, t[rt].pos = t[lson].pos;
        else t[rt].v = t[rson].v, t[rt].pos = t[rson].pos;
    }

    inline void pushdown(int rt){
        if(t[rt].tag){
            t[lson].tag += t[rt].tag, t[rson].tag += t[rt].tag;
            t[lson].v += t[rt].tag, t[rson].v += t[rt].tag;
            t[rt].tag = 0;
        }
    }

    inline void build(int rt, int l, int r){
        if(l == r){
            t[rt].v = f[l], t[rt].pos = l;
            return;
        }

        int mid = (l + r) >> 1;
        build(lson, l, mid),
        build(rson, mid+1, r);
        
        pushup(rt);

        // if(t[rt].pos == 0) cout<<"CTHisSB\n";
    }

    inline void update(int rt, int l, int r, int pos, int val){
        if(pos <= l and r <= n){
            t[rt].tag += val, t[rt].v += val;
            return;
        }pushdown(rt);

        int mid = (l + r) >> 1;
        if(pos <= mid) update(lson, l, mid, pos, val);
        if(n > mid) update(rson, mid+1, r, pos, val);

        pushup(rt);
    }

    inline tree query(int rt, int l, int r, int L, int R){
        if(L <= l and r <= R) return t[rt];
        pushdown(rt); 

        int mid = (l + r) >> 1;

        if(R <= mid) return query(lson, l, mid, L, R);
        else{
            if(L > mid) return query(rson, mid+1, r, L, R);
            else return min(query(lson, l, mid, L, R), query(rson, mid+1, r, L, R));
        }
    }
}

signed main(){
    freopen("a.in", "r", stdin), freopen("a.out", "w", stdout);
    // ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);

    qr(n), qr(q), cin>>(s+1);

    f[1] = 1; s[0] = '#', s[n+1] = '@';
    for(int i=2; i<=n; i++)
        f[i] = f[i-1] + P(s[i-1], s[i]);
    
    Tree::build(1, 1, n);

    while(q--)
    {
        int qr(op);
        switch(op){
            case 1:{int qr(p); char c; cin>>c; int now = P(s[p-1], c) - P(s[p-1], s[p]);
                    Tree::update(1, 1, n, p, now); now = P(c, s[p+1]) - P(s[p], s[p+1]);
                    Tree::update(1, 1, n, p+1, now); s[p] = c;  break; }
            default:{int qr(l), qr(r); cout<<s[Tree::query(1, 1, n, l, r).pos]<<"\n"; break;}
        }
    }
    

    return 0;
}

为了方便判断，我让 s[0]='#'，但交到 oj 上却输出了这个：

显然是返回了 0，但是毫无缘由，代码里注释部分是输出树上所有点的 pos，结果没有为 0 的。