[wikioi]线段树练习 2

http://codevs.cn/problem/1081/

#include <vector>

#include <iostream>

#include <string.h>



using namespace std;



const int MAXN = 100000;



struct Line {

    int left, right;

    int n;

};



Line tree[MAXN * 3];



void buildtr(int left, int right, int k) {

    tree[k].left = left;

    tree[k].right = right;

    tree[k].n = 0;

    if (left == right) return;

    int mid = (left + right) / 2;

    buildtr(left, mid, k * 2);

    buildtr(mid + 1, right, k * 2 + 1);

}



int query(int x, int k) {

    if (tree[k].left == x && tree[k].right == x) {

        return tree[k].n;

    }

    int mid = (tree[k].left + tree[k].right) / 2;

    if (x <= mid) return query(x, k * 2);

    else return query(x, k * 2 + 1);

}



int query(int l, int r, int k) {

    if (tree[k].left == l && tree[k].right == r) {

        //cout << "k:" << k << ",l" << l << "r," << r << ",n:" << tree[k].n << endl;

        return tree[k].n;

    }

    int mid = (tree[k].left + tree[k].right) / 2;

    if (r <= mid) {

        return query(l, r, k * 2);

    } else if (l > mid) {

        return query(l, r, k * 2 + 1);

    } else {

        return query(l, mid, k * 2) + query(mid + 1, r, k * 2 + 1);

    }

}



int update(int x, int y, int k) {

    int diff = 0;

    if (tree[k].left == x && tree[k].right == x) {

        diff = y - tree[k].n;

        tree[k].n = y;

        return diff;

    }

    int mid = (tree[k].left + tree[k].right) / 2;

    if (x <= mid) {

        diff = update(x, y, k * 2);

    } else {

        diff = update(x, y, k * 2 + 1);

    }

    tree[k].n += diff;

    return diff;

}



int add(int l, int r, int x, int k) {

    int diff = 0;

    if (tree[k].left == tree[k].right) {

        diff = x;

        tree[k].n += x;

        //cout << "diff:" << x << endl;

        return x;

    }

    int mid = (tree[k].left + tree[k].right) / 2;

    if (mid >= r) {

        diff = add(l, r, x, k * 2);

    } else if (mid < l) {

        diff = add(l, r, x, k * 2 + 1);

    } else {

        diff += add(l, mid, x, k * 2);

        diff += add(mid + 1, r, x, k * 2 + 1);

    }

    tree[k].n += diff;

    return diff;

}



int main() {

    int n;

    cin >> n;

    memset(tree, sizeof(tree), 0);

    buildtr(1, n, 1);

    for (int i = 1; i <= n; i++) {

        int x;

        cin >> x;

        update(i, x, 1);

    }

    int m;

    cin >> m;

    while (m--) {

        int c;

        cin >> c;

        if (c == 1) {

            int a, b, x;

            cin >> a >> b >> x;

            add(a, b, x, 1);

        } else if (c == 2) {

            int i;

            cin >> i;

            int res = query(i, i, 1);

            cout << res << endl;

        }

    }

}