POJ 3468 A Simple Problem with Integers

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不得不说，线段树学的太渣了，找了一份大神的代码贴上，以后仔细研读一下。

因为找不到出处，无法注明转载链接，请谅解。

 1 #include <cstdio> 2 #include <algorithm> 3 using namespace std; 4  5 #define lson l , m , rt << 1 6 #define rson m + 1 , r , rt << 1 | 1 7 #define LL long long 8 const int maxn = 111111; 9 LL add[maxn<<2];10 LL sum[maxn<<2];11 void PushUp(int rt) {12     sum[rt] = sum[rt<<1] + sum[rt<<1|1];13 }14 void PushDown(int rt,int m) {15     if (add[rt]) {16         add[rt<<1] += add[rt];17         add[rt<<1|1] += add[rt];18         sum[rt<<1] += add[rt] * (m - (m >> 1));19         sum[rt<<1|1] += add[rt] * (m >> 1);20         add[rt] = 0;21     }22 }23 void build(int l,int r,int rt) {24     add[rt] = 0;25     if (l == r) {26         scanf("%lld",&sum[rt]);27         return ;28     }29     int m = (l + r) >> 1;30     build(lson);31     build(rson);32     PushUp(rt);33 }34 void update(int L,int R,int c,int l,int r,int rt) {35     if (L <= l && r <= R) {36         add[rt] += c;37         sum[rt] += (LL)c * (r - l + 1);38         return ;39     }40     PushDown(rt , r - l + 1);41     int m = (l + r) >> 1;42     if (L <= m) update(L , R , c , lson);43     if (m < R) update(L , R , c , rson);44     PushUp(rt);45 }46 LL query(int L,int R,int l,int r,int rt) {47     if (L <= l && r <= R) {48         return sum[rt];49     }50     PushDown(rt , r - l + 1);51     int m = (l + r) >> 1;52     LL ret = 0;53     if (L <= m) ret += query(L , R , lson);54     if (m < R) ret += query(L , R , rson);55     return ret;56 }57 int main() {58     int N , Q;59     //freopen("D:acm.txt","r",stdin);60     scanf("%d%d",&N,&Q);61     build(1 , N , 1);62     while (Q --) {63         char op[2];64         int a , b , c;65         scanf("%s",op);66         if (op[0] == 'Q') {67             scanf("%d%d",&a,&b);68             printf("%lld\n",query(a , b , 1 , N , 1));69         } else {70             scanf("%d%d%d",&a,&b,&c);71             update(a , b , c , 1 , N , 1);72         }73     }74     return 0;75 }

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