dls的数据结构-树状数组

lowbit运算

modify:下表不能有0

题目链接：http://oj.daimayuan.top/course/15/problem/636
一个log的树状数组二分
#include<bits/stdc++.h>

using namespace std;
typedef long long LL;
const int N = 2e5+10;

LL tr[N], a[N];
int n;
int lowbit(int x){
    return x & (-x);
}

int modify(int x, LL v){
    for(int i = x; i <= n; i += lowbit(i)) tr[i] += v;
}
// 核心代码多理解
LL query(LL s){
    int pos = 0;
    for(int i = 20; i >= 0; i --){
        if(pos + (1 << i) <= n && tr[pos + (1 << i)] <= s){
            pos += (1 << i);
            // cout << pos << endl;
            s -= tr[pos];
        }
    }
    return pos;
}

int main(){

    int q; scanf("%d %d", &n, &q);
    for(int i = 1; i <= n; i ++) scanf("%lld", &a[i]), modify(i, a[i]);
    while(q--){
        int op; scanf("%d", &op);
        if(op == 1){
            int x, d; scanf("%d %d", &x, &d);
            modify(x, d - a[x]);
            a[x] = d;
        }
        else if(op == 2){
            LL x; scanf("%lld", &x);
            printf("%lld\n", query(x));
        }
    }
    return 0;
}

// 高维树状数组
#include<bits/stdc++.h>

using namespace std;
typedef long long LL;
const int N = 510;

LL tr[N][N], a[N][N];
int n, m;
int lowbit(int x){
    return x & (-x);
}

int modify(int x, int y, LL v){
    for(int i = x; i <= n; i += lowbit(i)){
        for(int j = y; j <= m; j += lowbit(j)) tr[i][j] += v;
    } 
}

LL query(LL x, LL y){
    LL sum = 0;
    for(int i = x; i ; i -= lowbit(i)){
        for(int j = y; j ; j -= lowbit(j)){
            sum += tr[i][j];
        }
    }
    return sum;
}

int main(){

    int q; scanf("%d %d %d", &n, &m, &q);
    for(int i = 1; i <= n; i ++){
        for(int j = 1; j <= m; j ++){
            int x; scanf("%d", &x);
            a[i][j] = x; modify(i, j, x);
        }
    }
    while(q--){
        int op; scanf("%d", &op);
        if(op == 1){
            int x, y, d; scanf("%d %d %d", &x, &y, &d);
            modify(x, y, d - a[x][y]);
            a[x][y] = d;
        }
        else if(op == 2){
            LL x, y; scanf("%lld %lld", &x, &y);
            printf("%lld\n", query(x, y));
        }
    }
    return 0;
}