代码随想录算法训练营第10天 | 232. 用栈实现队列

代码随想录算法训练营第10天 | 232. 用栈实现队列 | 225. 用队列实现栈

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232. 用栈实现队列

解

typedef struct {int intop, outtop;int instack[105], outstack[105];
} MyQueue;MyQueue* myQueueCreate() {MyQueue *queue = (MyQueue *)malloc(sizeof(MyQueue));queue->intop = queue->outtop = -1;memset(queue->instack, -1, sizeof(int) * 105);memset(queue->outstack, -1, sizeof(int) * 105);return queue;
}void myQueuePush(MyQueue* obj, int x) {while (obj->outtop >= 0) {obj->instack[++obj->intop] = obj->outstack[obj->outtop--];}obj->instack[++obj->intop] = x;
}int myQueuePop(MyQueue* obj) {while (obj->intop >= 0) {obj->outstack[++obj->outtop] = obj->instack[obj->intop--];}return obj->outstack[obj->outtop--];
}int myQueuePeek(MyQueue* obj) {while (obj->intop >= 0) {obj->outstack[++obj->outtop] = obj->instack[obj->intop--];}return obj->outstack[obj->outtop];
}bool myQueueEmpty(MyQueue* obj) {while (obj->intop >= 0) {obj->outstack[++obj->outtop] = obj->instack[obj->intop--];}if (obj->outtop < 0) {return true;}return false;
}void myQueueFree(MyQueue* obj) {free(obj);
}

225. 用队列实现栈

题目链接

解

用环形队列实现

const int max = 105;typedef struct {int front1, back1;int front2, back2;int queue1[105], queue2[105];
} MyStack;MyStack* myStackCreate() {MyStack *stack = (MyStack *)malloc(sizeof(MyStack));memset(stack->queue1, -1, sizeof(int) * max);stack->front1 = stack->back1 = 0;memset(stack->queue2, -1, sizeof(int) * max);stack->front2 = stack->back2 = 0;return stack;
}void myStackPush(MyStack* obj, int x) {obj->queue1[obj->front1] = x;obj->front1 = (obj->front1 + 1) % max;return;
}int myStackPop(MyStack* obj) {int ret;while (obj->back1 != obj->front1-1) {obj->queue2[obj->front2] = obj->queue1[obj->back1];obj->front2 = (obj->front2 + 1) % max;obj->back1 = (obj->back1 + 1) % max;}ret = obj->queue1[obj->back1];obj->back1 = (obj->back1 + 1) % max;while (obj->back2 != obj->front2) {obj->queue1[obj->front1] = obj->queue2[obj->back2];obj->front1 = (obj->front1 + 1) % max;obj->back2 = (obj->back2 + 1) % max;}return ret;
}int myStackTop(MyStack* obj) {int ret;while (obj->back1 != obj->front1-1) {obj->queue2[obj->front2] = obj->queue1[obj->back1];obj->front2 = (obj->front2 + 1) % max;obj->back1 = (obj->back1 + 1) % max;}ret = obj->queue1[obj->back1];obj->queue2[obj->front2] = obj->queue1[obj->back1];obj->front2 = (obj->front2 + 1) % max;obj->back1 = (obj->back1 + 1) % max;while (obj->back2 != obj->front2) {obj->queue1[obj->front1] = obj->queue2[obj->back2];obj->front1 = (obj->front1 + 1) % max;obj->back2 = (obj->back2 + 1) % max;}return ret;
}bool myStackEmpty(MyStack* obj) {if (obj->front1 == obj->back1) {return true;}return false;
}void myStackFree(MyStack* obj) {free(obj);
}/*** Your MyStack struct will be instantiated and called as such:* MyStack* obj = myStackCreate();* myStackPush(obj, x);* int param_2 = myStackPop(obj);* int param_3 = myStackTop(obj);* bool param_4 = myStackEmpty(obj);* myStackFree(obj);
*/