第一种方法，暴力法：

    1. typedef struct {
    2.     int *stack;
    3.     int current_size;
    4. } MinStack;
    6. /** initialize your data structure here. */
    8. MinStack* minStackCreate() {
    9.     MinStack *ms=(MinStack*)malloc(sizeof(MinStack));
    10.     ms->stack=(int*)malloc(20000*sizeof(int));
    11.     ms->current_size=0;
    12.     return ms;
    13. }
    15. void minStackPush(MinStack* obj, int x) {
    16.     obj->stack[obj->current_size]=x;
    17.     obj->current_size++;
    18. }
    20. void minStackPop(MinStack* obj) {
    21.     obj->current_size--;
    22. }
    24. int minStackTop(MinStack* obj) {
    25.     if (obj->current_size==0) return 0;
    26.     else
    27.         return obj->stack[obj->current_size-1];
    28. }
    30. int minStackMin(MinStack* obj) {
    31.     if (obj->current_size==0) return 0;
    32.     int temp=obj->stack[0];
    33.     for (int i=0;i<obj->current_size;++i) {
    34.         if (obj->stack[i]<temp)
    35.             temp=obj->stack[i];
    36.     }
    37.     return temp;
    38. }
    40. void minStackFree(MinStack* obj) {
    41.     free(obj->stack);
    42.     free(obj);
    43. }
    45. /**
    46.  * Your MinStack struct will be instantiated and called as such:
    47.  * MinStack* obj = minStackCreate();
    48.  * minStackPush(obj, x);
    50.  * minStackPop(obj);
    52.  * int param_3 = minStackTop(obj);
    54.  * int param_4 = minStackMin(obj);
    56.  * minStackFree(obj);
    57. */

    leedcode通过：

    1. 执行用时：96 ms, 在所有 C 提交中击败了11.20% 的用户
    2. 内存消耗：12.8 MB, 在所有 C 提交中击败了61.38% 的用户

    第二种方法，使用两个栈

    4. typedef struct {
    5.     int *stack;
    6.     int *min_stack;
    7.     int current_size;
    8. } MinStack;
    10. /** initialize your data structure here. */
    12. MinStack* minStackCreate() {
    13.     MinStack *ms=(MinStack*)malloc(sizeof(MinStack));
    14.     ms->stack = (int*)malloc(8000*sizeof(int));
    15.     ms->min_stack = (int*)malloc(8000*sizeof(int));
    16.     ms->current_size = 0;
    17.     return ms;
    18. }
    20. void minStackPush(MinStack* obj, int x) {
    21.     obj->stack[obj->current_size]=x;
    23.     if (obj->current_size==0) {
    24.         obj->min_stack[obj->current_size]=x;
    25.     }
    26.     else {
    27.         if (x < obj->min_stack[obj->current_size-1]) {
    28.             obj->min_stack[obj->current_size]=x;
    29.         }
    30.         else {
    31.             obj->min_stack[obj->current_size]=obj->min_stack[obj->current_size-1];
    32.         }
    33.     }
    34.     obj->current_size++;
    35. }
    37. void minStackPop(MinStack* obj) {
    38.     if (obj->current_size!=0)
    39.         obj->current_size--;
    40. }
    42. int minStackTop(MinStack* obj) {
    43.     if (obj->current_size!=0)
    44.         return obj->stack[obj->current_size-1];
    45.     return 0;
    46. }
    48. int minStackMin(MinStack* obj) {
    49.     if (obj->current_size!=0)
    50.         return obj->min_stack[obj->current_size-1];
    51.     return 0;
    52. }
    54. void minStackFree(MinStack* obj) {
    55.     free(obj->stack);
    56.     free(obj->min_stack);
    57.     free(obj);
    58. }
    60. /**
    61.  * Your MinStack struct will be instantiated and called as such:
    62.  * MinStack* obj = minStackCreate();
    63.  * minStackPush(obj, x);
    65.  * minStackPop(obj);
    67.  * int param_3 = minStackTop(obj);
    69.  * int param_4 = minStackMin(obj);
    71.  * minStackFree(obj);
    72. */

    leedcode通过：

    1. 执行用时：24 ms, 在所有 C 提交中击败了90.57% 的用户
    2. 内存消耗：12.7 MB, 在所有 C 提交中击败了66.92% 的用户